Ryan Hunter-Reay was in no doubt about what he had to do at Baltimore: win. And moreover, win by multiple positions over championship leader Will Power if he was to have any chance of closing the gap between them in the IZOD IndyCar Series points standings, to the point where it was still realistically possible for Hunter-Reay to continue his challenge for the title at the season finale in two weeks time at Auto Club Speedway at Fontana.

That's why a starting grid position of 12th place had been so painful to Hunter-Reay, especially as Will Power had so effortlessly glided to pole position for the 75-lap race on the the 2.04-mile, 13-turn track temporary street circuit. Power duly led the field to the green flag and immediately started to pull away from Scott Dixon, leaving Hunter-Reay with no option but to make use of push-to-pass right from the start and begin picking off positions down the front straight on the opening laps.

Dixon was another driver still in with a shot at the title, but it was clear he had nothing of the pace required to keep up with Power at the front, let alone challenge for the lead. Indeed, he was helpless to prevent Sebastian Bourdais slicing past him into turn 1 at the start of lap 5. Bourdais was looking on fine form despite still being in pain from the crash he'd had with Josef Newgarden at Sonoma, which had left Newgarden sidelined this weekend and Champ Car veteran Bruno Junqueira drafted in as a replacement at Sarah Fisher Hartman Racing.

The opening laps were full of near-misses, light contact and white knuckle moments as the beginnings of pit stop strategies started to form with JR Hildebrand, EJ Viso, Rubens Barrichello and Graham Rahal opted to come in early on obvious three-stop cycles. But then on lap 9 Ed Carpenter was the first driver in the race to misjudge the run through the remodelled chicane on the front stretch, intended to redirect cars away from dangerous bumps around railroad tracks. The #20 car was sent skidding into a crunching impact with the wall where it came to an emphatic halt, triggering the first full course caution of the afternoon.

"I was trying to gain time through the chicane and I just pushed too hard and hit the wall," said Carpenter. "I really feel badly for our crew guys and the Fuzzy's Vodka folks. I am pretty frustrated. We had an opportunity to pick up some points and have a good street race. It was a good weekend for us overall and this is a disappointment for our team."

There was the start of a light shower moving over the region during the ensuing caution, but the teams had been reassured that it would be brief and would have little impact, so no one was inclined to switch to wet tyres on such minor provocation - even when the sprinkles started to take on the appearance of full-blooded rain drops.

The race resumed, but on lap 14 two separate incidents at turn 6 triggered a quick return to yellow: Mike Conway was spun around by a tap from Helio Castroneves, while Bruno Junquiera was punted into a spin by JR Hildebrand. Conway was able to carry on, but Junqueira's engine stalled which brought out the caution and warranted a drive-thru penalty for Hildebrand.

This was a sideshow compared with the weather channel: the rain was still falling, and contrary to the forecasts the teams were receiving it still wasn't going away. The longer it went on, the more treacherous parts of the circuit were getting for race cars on slick tyres - as evidenced by Bourdais spinning behind the safety car and losing three positions, despite his pleas to be allowed to retake his spot because it had happened under yellow. Even with this latest evidence, most of the drivers held their nerves and stayed out, betting on the weather drying up soon.

As soon as the field got back up to speed down the front stretch on lap 18, it was clear that this had been a horrible mistake: the amount of water thrown into the air betrayed just how wet the slick streets now were. Helio Castroneves, EJ Viso and Justin Wilson were all rapid visitors to the run-off areas and it was inevitable that someone would end up buried in the tyre wall at turn 1 - it just happened to be Marco Andretti next time by, bringing out the third caution.

"I messed up and put the car in the wall," he said. "We ended up driving an ill car for the rest of the day."

This time the majority of drivers led by Will Power, Sebastien Bourdais, Scott Dixon and Simon Pagenaud had no qualms about discarding the weather forecasts and coming in for wet tyres - it was a simple matter of survival. Unless you happened to be playing all-in poker like Ryan Hunter-Reay, and he staked everything on slicks by staying out with his Andretti Autosport team mate James Hinchcliffe. It was either a work of genius that could win him the race, or else he'd just thrown away his last chance of the championship.

Hunter-Reay and Hinchcliffe led Wilson, Barrichello, Takuma Sato and Graham Rahal to the line on lap 21 ahead of Will Power and Scott Dixon who were the first of the most recent drivers to have pitted for wet tyres; but the restart was brief before the yellows were back out again, this time for Dario Franchitti who had been spun at turn 1 by a hefty thump from behind by Simona de Silvestro.

The subsequent caution worked to Hunter-Reay's advantage: the rain stopped, and even while the cars were circulating behind the safety car the track was drying all the time. Suddenly staying on slick tyres no longer appeared as suicidal as it did; in fact, it was the cars on wet tyres that started to fret as the rain water quickly drained away and a dry line started to appear all around the circuit.

It was to general amazement, then, that Ryan Hunter-Reay ducked into pit lane on lap 23. Startled, Will Power and the Penske team instinctively decided to do the opposite to Hunter-Reay and stayed out; but it appeared that it had been a bluff by the Andretti crew, as the team changed the #28's tyres not to a set of wets but to a new set of slicks, getting one of their two pit stops out of the way even as Power had left himself stranded out on track still on the increasingly inappropriate wet tyres.

At the restart on lap 25, Hinchcliffe, Sato and Rahal were at the front ahead of Power and Dixon. A poor restart for Hinch put Sato into the lead, which the Rahal Letterman Lanigan driver liked the feel of so much that he stayed in front for the next seven laps, and it didn't take long during that time before Power, Dixon and the rest of those who had switched to wet tyres sheepishly came back onto pit road to change back to slicks again.

The cautions were back out again when James Jakes buried his car into the tyres at turn 4 on lap 32, during which time Sato opted to start the visits to pit road. Sebastien Bourdais' time there proved somewhat terminal: after some impressive early laps he had fallen down the running order and was now climbing out of his car, done for the day with suspension issues.

"I thought it was something was sitting on the right rear, or I thought I had a cut in the right rear, but that wasn't it," he said. "It was something in the suspension."

Sato was still in front for the restart, but appeared oddly underpowered as the green flag came out. His slow pace checked up the cars behind and gave Simon Pagenaud the chance to spring from sixth place round the outside down the front straight, and then dive across the front of the field to take the inside line into turn 1. A near-unbelievable manoeuvre that somehow came off.

Once again, however, it was a short-lived green, with James Hinchcliffe crawling to a halt in turn 2 after slicing his tyre following contact with Mike Conway. Initially Hinch climbed out of the #27 thinking his day was done, but after surveying the damage he climbed back in, the car was refired, and following a trip onto pit road he was able to continue the race after all - albeit off the leap lap for the rest of the day.

"Today was a clinic in what not to do," said an embarrassed Hinchcliffe of the incident. "Pretty ashamed of the whole deal, it's just not what the Go Daddy team is capable of."

Another attempt at a restart was foiled by Simona de Silvestro aping Ed Carpeter's earlier encounter with the frontstretch wall after cutting the chicane too fine: "I hit the curb in the chicane and it ended our day," she confessed. "Until then it was kind of a crazy race. We made some positions; we don't know where we would have finished. This time it's kind of my fault. It's a shame because we were doing really well.

After that, the race finally got back to a sustained period of green flag running, with Pagenaud retaining the lead ahead of Hunter-Reay at the restart on lap 43. However, this period saw the end of the race for three more competitors.

First there was Takuma Sato retiring in the pits on lap 50, with an issue that likely explained why he'd been so slow on that earlier restart: "I think a fuel pressure problem," he said. "The engine started coughing and I started to lose power; especially on the restart, there was just no power and a bunch of the drivers overtook me. Every restart was difficult and in the end it was difficult to select the gears due to some engine response I think. In the end we had to stop which is a big shame."

Two laps later, Tony Kanaan became the latest victim of the wall beyond the front stretch chicane. While his contact was relatively light and he was able to continue round to the pit entrance, the impact had been terminal on his left rear suspension. "We had a pretty good car, I was just pushing hard on the last lap before a pit stop and I made a mistake," he said.

And then on lap 64 it was Bruno Junqueira's turn to retire on pit road after a similar incident to Kanaan's. "I brushed the wall after going through the chicane," he said. "My left rear suspension was broken and we couldn't continue on in the race. I was very sorry and frustrated because I had been making up distance all afternoon."

Finally the yellows were out again with ten laps of the race to go, this time for Charlie Kimball whose engine appeared to have blown, bringing the car to a halt in turn 3. "It's a shame to have something behind me go wrong around lap 65, but we proved we have the speed all weekend," he said, already looking forward to the final race of the season at Fontana.

By this point, the final round of fuel stops had already cycled through and Hunter-Reay had popped back in front of Pagenaud on his exit from pit road ahead of Dixon, Power and Franchitti. But the actual leader of the race was Ryan Briscoe, who was attempting the near-impossible feat of trying to stretch his fuel all the way from lap 41 to the end of the race and thereby gain position by making one stop fewer than the others. It had looked like a doomed plan, but the caution for Kimball and the ensuing gas-saving laps under yellow kept the dream alive.

However Briscoe was slow at the restart on lap 70, and just as he had done multiple times already this afternoon Hunter-Reay needed no second invitation to floor the throttle the minute the green flag came out. He blasted away from Briscoe, taking Pagenaud along with him.

"Everyone had been going late, the green flag was actually coming out before the leaders were accelerating," explained Hunter-Reay of his ability to read the restart to such accuracy. "I caught wind of that so I just started to focus on the green flag instead of focusing on the guy next to me, and Briscoe got jumped on that one but the green flag was flying when he was still sitting there in first gear.

"I mean I feel sorry for him," he said. "Well I don't really feel sorry. But you know what I mean!" he laughed.

The Penske team was furious: as far as they were concerned, this was a clear case of Hunter-Reay having jumped the restart. Roger Penske was quickly demanding that race control issue a penalty to the #28; but Beaux Barfield reviewed the footage, determined that Hunter-Reay had maintained position behind Briscoe until the green flag came out, and only then had made his break. As far as IndyCar was concerned it was a legal move, and there would be no penalty forthcoming. The thunderclouds that suddenly appeared over Baltimore's downtown area directly over the Penske pit area were entirely non-meteorological.

Briscoe probably still wouldn't have made the distance from here anyway if not for one last caution that came seconds later when Mike Conway and Rubens Barrichello tried squeezing through turn 4 side-by-side. That was never going to work, and one of them was going to end up in the wall: as luck had it, Rubens made it through and Conway was the one stuck in the tyres. He was then collected by the incoming Justin Wilson, who wedged himself in underneath the AJ Foyt car with the help of a shove from Graham Rahal arriving on the scene.

James Hinchcliffe also arrived to find the road ahead totally blocked, and so the yellows came out once more to remove the traffic jam; as track workers strained to prise apart Conway and Wilson's mounted cars, the irony of this all occurring at the corner of Conway Street wasn't lost on anyone.

"On that last restart, I got a couple cars when they bottled up on the hairpin, but then I tried to go in too quick on the next corner and I was into the tyres" said Conway of the incident. "Tough way to end."

Marco Andretti was another to arrive on the scene, at the end of a very long afternoon for him which included his own trip into the tyre barrier. "It was a war zone out there today," he said. "I had a piece of carbon fibre fly up and hit my helmet which took a big gash out of it and we broke two front wings," he signed, happy to be done with Baltimore and more than ready to be back to an oval track in a fortnight.

That left a two lap shootout to the chequered flag: Hunter-Reay was in no mood to lose this race now, and he controlled proceedings with a grim determination until the chequered flag had come out. He'd done what he'd set out to do: the race win was his.

"It's massive," said Hunter-Reay. "I'm just trying to catch my breathe. Those restarts were crazy, crazy, crazy."

He'd done all he could do, and now all that remained was to see where Power finished to know whether it had been enough to make sufficient in-roads into the Australian's lead in the points standings.

With the aid of that final pile-up caution, Ryan Briscoe had made his fuel last to the chequered flag although he'd promptly run dry almost immediately afterwards. That had given him second place ahead of Simon Pagenaud in third, while Scott Dixon had to make do with fourth place. Still no sign of the championship leader.

In fact it had been a rough final couple of laps for Power: he'd found himself barged aside at the hairpin by none other than Rubens Barrichello, which also allowed Oriol Servia to get past. Power was able to get back past Servia but Barrichello was already too far ahead - and probably permanently crossed off Power's Christmas card list for that overtaking move. Barrichello duly picked up fifth place, and Power finally came home in sixth.

In terms of points, that meant Power was on 453pts to Hunter-Reay's 436pts: just 17pts between them going into the final round at Auto Club Speedway in Fontana, California on September 15. But perhaps most significantly, that's an oval race: while Power has three wins this season they've all been on road courses. Ovals are not Power's forte, whereas three of Hunter-Reay's four wins have been on ovals. That means that despite the apparent points difference between the two, the odds are very much even going into that final race of the year.

"It never comes easy," said Power of his championship prospects. "We just have to do our best and fight like a dog till the end. We'll come out swinging."

"We still have a shot," said a determined Hunter-Reay. "We all want it bad enough, we can go get this thing. The team deserves it; it's a matter of if we can put it together."

But that's for next time. First, there was the small matter of Hunter-Reay's victory in Baltimore to celebrate.

"I'm super happy for Ryan," said his Andretti Autosport team mate James Hinchcliffe. "He drove a blinder and after all the bad luck he has been through this season, he deserves this title. We will go to Fontana and do everything we can to help him win."

In two weeks' time, we'll know if that's enough, or whether Will Power had finally clinched his long-delayed first IZOD IndyCar Series title. Right now, it's impossible to call it.

Full race results and times from all practice, qualifying and warm-up sessions are available, as are the current IZOD IndyCar Series championship standings.