Greg Biffle ran a solid race all afternoon, but it appeared that he and his Roush Fenway Racing team might have been out-smarted on pit stop strategy by their Hendrick Motorsports counterpart as the race approached its climax - only for an engine blow-out for race leader Jimmie Johnson to hand the advantage back to Biffle at the critical moment.

"We were able to close in on the #48 there on the end," said Biffle after taking the chequered flag. "[I] was catching him and then he had the engine failure.

"It was going to be a great race no matter what. I felt like I could catch him but we will never know. Passing him might have been a different story but I certainly think with seven to go I could have probably pulled up close to him."

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Johnson had initially been sent to the back of the field for the start after an engine change made on Saturday, putting him alongside his Hendrick Motorsport team mate Dale Earnhardt Jr. who had needed to take to his backup car after wrecking in practice. By contrast, Biffle had started from a drama-free if slightly anonymous 13th place at the green flag.

Mark Martin had been looking in fine form as the race got underway, converting pole position into an easy lead for the first 35 laps ahead of Matt Kenseth until the start of the first round of pit stops under green. After brief stints out front for Brad Keselowski, Jimmie Johnson and Sam Hornish Jr., Martin was back in charge on lap 46 with his Michael Waltrip Racing team mate Martin Truex Jr. now in second.

However, the biggest mover among the leaders in this second phase of the race was Kasey Kahne, who worked his way past first Kenseth and then Truex, and then gradually closed up on the back of Martin so that by lap 64 it looked like just a matter of minutes before Kahne - driving the #5 Hendrick Motorsport car than he took over from Martin at the beginning of 2012 - would take over the race from the veteran.

But before that could happen, Bobby Labonte spun the #47 in turn 4 right in front of the leaders while battling with Juan Montoya at the back of the lead lap. "The #47 got turned around there and we got jammed up and the #5 got into the back of him," explained Martin.

That sent Martin spinning into pit road in response right through the fortunately vacant pit stalls. But the crowd watched in horror as the #55 Aaron's car continued its slow spin past the opening in the pit wall located between the stalls of Kasey Kahne and Jimmie Johnson that leads to the garage area: and then the hard edge of the resumption of the pit wall came into play, drilling right into the driver's side of the car by a depth of something around four feet.

If that had lined up with the driver's seat then it would have done devastating harm to the occupant; pure chance meant that the penetration took place just inches behind the seat itself, although that resulted in a rupture of oil and fuel lines that sparked an immediate fire. The Hendrick Motorsports crews were told to grab fire extinguishers and help Martin get clear, and the crowd cheered as Martin popped up through the smoke and the extinguisher discharge looking miraculously none the worse for wear.

Martin was quickly reassuring anxious fans that, "It was not as bad as it looked." He did admit that he'd been worried, though: "I was concerned right before I hit it. I thought, 'This could be one of those sudden stops!'"

"The guys had the #55 car basically land in our pit, and they all survived that fortunately," said Kasey Kahne later. "Thankfully when Mark Martin slid down pit road, he ended up halfway into our pit. One of our guys got hit a little bit by a tyre. His oil tank exploded and stuff. That was really close to a really bad situation but it turned out all right."

Kahne had also spun in the accident and went through the grass, suffering front fender damage to his car which meant that once things had calmed down on pit lane, he needed an extended series of visits for repairs. "They fixed my car," said Kahne. "I had some right front damage there. They patched it up pretty nicely. It didn't drive perfect after that, but it did drive pretty closely to how it was, which was really nice.

Calling the accident "unfortunate," Martin said there had been nothing that he could have done to control the point of impact once the accident had started. "I fought it with everything I had. With where I came from and the speed I came from and the confines of pit road, I couldn't miss it," he said.

Asked whether the accident pointed out a serious design flaw in the pit wall construction, Martin shook his head. "I'm not sure you can ever completely fix something like that. That was a pretty freak angle that I got at that. I'm not sure what you could do."

Brad Keselowski was a little more alarmed about the incident that he'd seen: "Over the course of time, we always get complacent and think that we've hit all the buttons on the safety side," he said. "Then you see something like that. It shows you why you have to never quit working at making these cars and tracks safer."

Martin's grace under fire - and in the face of crushing disappointment from what had looked set to be a very strong day for the five-time winner at Michigan in the past - was in contrast to some markedly frayed tempers up and down pit road. Even long time team mates Jeff Gordon and Dale Earnhardt Jr. were fast falling out at Michigan on Sunday afternoon.

Gordon was furious with a move that the #88 pulled off at the restart for Martin's accident that saw Earnhardt go four-wide with Gordon, Jeff Burton and Regan Smith - and then slid up the track nearly wiping out the #24. "He can thank me for not wrecking him," Gordon radioed his pit crew after the near miss. "That was stupid."

When he was out of the car later on, Gordon elaborated: "I didn't think it was very smart what he did. He took me four-wide and then he slid up in front of me. If I hadn't checked up, I would have wrecked him and a bunch of us," he fumed. "In that moment, he wasn't treating me like a teammate ... I don't care who I'm racing out there; I'm going to show my displeasure if I'm not happy about something. But that one was pretty close.

"I wasn't doing anything different than I would have done," Gordon continued. "He's racing hard. I don't blame him for taking me four-wide. But if you're going to take a guy four-wide, don't come sliding up the racetrack because that is going to wreck you and other people."

There were short tempers in the Richard Childress Racing camp as well, with Kevin Harvick left fuming when early adjustments to the car left the #29 in a far worse state than when he'd started. The heated conversation with his pit crew got to the point where team owner Richard Childress himself came on the air and told them to just get on with it: ""We got what we got here, arguing ain't gonna get us nowhere!" he snapped.

Harvick's team mate Jeff Burton, meanwhile, was furious when he was placed by NASCAR behind Marcos Ambrose for the next restart, which was needed following a quick new caution when contact from Ambrose tipped Regan Smith into a spin. Even less happy about the incident was Smith himself.

"Ambrose is just driving over his head," fumed Smith. "I don't know if it is because he won last week, he's got extra pressure or what. He's been doing it all day. He's almost wrecked four times that I've seen. Unfortunately, four tyres are better than two, and I was four."

Ambrose was conciliatory when the two met up after the end of the race. "I feel terrible for him, I didn't mean to get into him," said Ambrose. "I got down in there and he came off my side of the car and I was trying to get out of there for him and just caught him on the way past. I feel bad for him. You can't take it back, all you can say is sorry."

Another quick caution came out on lap 89 when Joey Logano hit the wall in turn 3 on two consecutive laps and left debris on the track, and after a flurry of pit stops it meant that Truex Jr. led at the green flag ahead of Kenseth, Greg Biffle, Carl Edwards and Sam Hornish Jr.; Kenseth had a shaky moment into the first turn and temporarily dropped back several positions.

Further back, Jeff Gordon was also off the pace - and his engine sounded very sick. As well as Jimmie Johnson's Saturday engine change, Tony Stewart - also running a Chevrolet built by the Hendrick Motorsports shop - had suffered a valve spring issue affecting one of the engine cylinders. Gordon confirmed that the same fault had hit him, too.

"A valve spring, just running along there and all of a sudden dropped a cylinder," said Gordon. "The #14 had that same issue. Got our fingers crossed for all the other Hendrick engines out there - this is a tough place on engines. We rarely have these issues and it's unfortunate to have this one here today. It's the kind of year we have been having."

It was not the way he'd been hoping to follow up his race win last weekend. "I was hoping after Pocono we could carry some momentum and not have these kinds of back-to-back weekends, but that's not the case. We go on to Bristol and fight hard there."

Michigan is notoriously hard on engines, being flat-out for a higher proportion of the two-mile circuit than almost any other track that the Sprint Cup cars race on, but that was small consolation to reigning Cup champion Tony Stewart who spent ages in the pits trying to get his car repaired before finally having to concede defeat.

"I appreciate everybody at the Hendrick engine department," said the owner-driver. "We had three different engine tuners down there trying to get it fixed for us. It wasn't for a lack of effort. It's uncommon to have a problem like this."

As the race passed the halfway mark - and inclement weather not even remotely on the horizon this weekend at Michigan - Greg Biffle moved passed Truex to take the lead for the first time of the day, shortly before the next round of pit stops saw the off-sync group of Dale Earnhardt Jr., Jimmie Johnson, Denny Hamlin, Marcos Ambrose and Kasey Kahne take over the top five for a time.

By lap 130, even these cars had cycled through pit lane for what they hoped would be their penultimate stop of the day. Biffle, Truex and Kenseth were back in control of the race, but they still had to fit in two more stops in the remaining 70 laps. Lurking back in eighth position with only one more visit to pit road to go, Earnhardt and his like-minded companions looked to have the whip hand.

That situation changed when Kurt Busch hit the wall in turn 3 on lap 136. The leading group realised the danger they were facing and now fitted in their own last-but-one stops of the day, essentially equalising the pit stop situation albeit leaving the Hendrick trio of Earnhardt, Johnson and Kahne in control for the restart on lap 143. That green flag barely lasted a lap before Juan Montoya's tyre blew and shredded his car bodywork, scattering debris all over the speedway.

"Well, anything that could go wrong today did," sighed Montoya, after nursing home the patched-up #42 to the end of the race in 26th place.

Matt Kenseth's hopes of a race win were also dealt a blow at the next restart on lap 148 when he too suffered a flat tyre. While fortunately it didn't blow apart like Montoya's did, it still wrecked his hopes of a strong finish.

"We just didn't really pit for fuel at the right time, but Greg was on the same strategy and won the race," Kenseth explained after finishing in 17th position. "We kept getting stuck in the wrong lane on restarts and had some sub-par pit stops and had a flat tyre and just couldn't recover from that."

Jimmie Johnson was now the strongest of the Hendrick cars and pulled ahead of Earnhardt in turn 4 for the lead on lap 152, with Brad Keselowski, Kasey Kahne and Clint Bowyer in close pursuit.

Earnhardt was one of the first to come in for his final pit stop on lap 163 and most of the cars followed suit soon after, but Sam Hornish Jr. held out for a dozen laps including one that saw him clocked at a phenomenal 211 mph going into turn 1 as he tried to make the most of his shifted strategy.

Trevor Bayne pitted a lap later, but his next run lasted just five laps before a tyre problem sent him into the wall on lap 180 to bring out the seventh caution of the afternoon with 20 laps remaining.

"We blew a left front," Bayne explained. "We had two runs of taking just rights and that bit us there. I slid them getting in the box and flat spotted the tyre. It had a little vibration before it blew. I was hoping it let go on the straightaway and it did let go finally - when it did it blew up and took us right into the wall."

The sequence of pit stops had left Brad Keselowski out in front - to the astonishment of Johnson and his pit crew who couldn't quite figure out how the Penske driver had managed to pull that one off. No matter, Johnson and his remaining cohorts - Kahne and Earnhardt - were looking in strong form to take the win and possibly lock up all the podium positions as well, providing of course that there were no late recurrences of the Chevy engine issues.

Kahne was still nursing the damage from his early spin and fell back at the restart, while Greg Biffle surged up two spots from fifth place to be in the ideal position to watch Johnson mount his assault on Keselowski for the lead, which finally paid off on lap 190 in turn 2. Biffle lined up the #2 and followed Johnson through next time around, but now Johnson already had a one second lead and looked unbeatable with just half a dozen laps remaining.

"I was closing in on him and I don't know if I would have got him in those eight laps or not," admitted Biffle. "I found some speed in the top line down there in three and four and was coming on him ... It would have been a hell of a run to the end."

Then Johnson was abruptly off the pace: and the problem was immediately apparent, as smoke and fluid poured out of the #48's exhaust. The engine had just died on him - the third Chevy of the race, and Johnson's second of the weekend. It was a cruel way to lose a seemingly certain race victory, and it clearly hurt the five-time champion: usually the most media-friendly of all the drivers in the paddock, this time Johnson departed the speedway without a single word to anyone. There was even a long pause before he finally posted on Twitter: "Thanks everyone, today was a tough one. We blew up & I'm disappointed, not much else to say. Now it's on to Bristol."

After that drama, the green-white-chequered restart proved anti-climactic: Biffle powered away and Keselowski had nothing left to offer in resistance. The chequered flag dropped with Biffle almost half a second ahead of Keselowski, who just managed to hold on to second ahead of Kahne and Earnhardt.

"That was a wild race," said Biffle in victory lane. "The race today, my car was super good at the beginning of the race when the track was kind of green and we got going there but once I got on restarts and in traffic I wasn't that good. I just kept working on it and trying different things, dragging the brakes in the corner to get it go a little better.

"We were so good out front," he continued. "Once I passed a car I could run the next guy down by a half-a-second a lap. I knew once we got out front we would be tough to beat and that was the case."

Keselowski had no complaints about finishing second. "He just did a great job," he said of Biffle. "He had a fast car and passed me legit and I couldn't keep up with him. Between the #48, the #16 and the #55, those three cars were just I think the class of the field today."

"There's nothing I want more I want than to win here at Michigan and you can feel a little bit of foreshadowing going on with the Chase coming on and those cars running right by each other," Keselowski added. "It's an honour to get to race with guys like Jimmie and Greg and be door-to-door. If my team can continue to execute like they did today I think we've got a real good shot at this championship so I'm very, very proud."

Biffle's win puts him on top of the NASCAR Sprint Cup championship points standings, 20pts ahead of team mate Matt Kenseth with just three races remaining now to the Chase cut-off that takes place after Richmond on September 8. No one is yet mathematically a lock for a Chase position, but it would take a seismic event for Biffle and Kenseth to miss out now.

"I know that a lot of people don't expect us to win the championship and don't expect us to compete for the title," said Biffle. "But I don't care what they say or who they want to talk about or what they want to talk about. We will be a factor when it comes down to Homestead, I promise you that."

Dale Earnhardt Jr. is in third place in the standings just ahead of Jimmie Johnson, and Brad Keselowski is also looking a sure thing for a Chase spot in fifth place. While he had also made the Chase in 2011 it had been through a "most wins" wild card, and he said that he was enjoying being a genuine top ten Chase qualifier this time around.

"I can taste the legitimacy of being a championship contender," he laughed. "We're going to keep them honest through this Chase. That's our goal."

The wildcard positions are currently held by Kasey Kahne and Ryan Newman. Newman finished the Pure Michigan 400 in a solid eighth place, no mean feat for a man suffering a severe bout of stomach 'flu and at one point looking like he might have to call in a replacement driver to pilot the #39.

Kahne and Newman could still be thwarted by one of the other drivers on the periphery of the top ten getting one or more wins at Bristol, Atlanta and Richmond: Carl Edwards, Kyle Busch, Jeff Gordon, Marcos Ambrose and Joey Logano are the big names amongst those still in with a chance of making it into the post-regular season fight for the Sprint Cup championship.

Full race results, Saturday practice times and championship standings are all available.