There was a time, not so long ago, when Sonoma could be relied upon to deliver the quietest, least interesting and most incident-free free race of the year as far as race fans were concerned. And not just the quietest outing of the IZOD IndyCar Series season either, but pretty much the dullest race of any championship anywhere.

Where did such easygoing times go? Such torpor was certainly not in evidence in this year's GoPro Grand Prix of Sonoma on Sunday. Far from it, this was was eventful and exciting as you could hope for from an open wheel race on a permanent road course. And that was even before the controversy erupted during the final round of pit stops on lap 64, which could end up having huge repercussions for the entire 2013 championship.

It had been a fast and furious affair long before that, however. Polesitter Dario Franchitti leapt away at the green flag even as his Ganasssi team mate Scott Dixon was working hard to fend off a determined lunge for second from Penske's Will Power through the first corners of the 2.385-mile, 12-turn Sonoma Raceway. There was less happy news for the third Ganassi car deeper in the field, however: Mid-Ohio race winner Charlie Kimball got caught out when the traffic bunched up through turn 2, made contact with Helio Castroneves and spun onto the dirt at the top of the hill. That brought out an immediate full course caution while the #83 was recovered to pit road for a checkover; already on pit road was the #67 of Josef Newgarden with gearbox issues on top of front wing damage for a clash with EJ Viso on the opening lap.

At the restart on lap 3, the Ganassi pair at the front made heavy weather of getting going which handed Will Power a golden opportunity to attack Dixon for the second spot again. Dixon held fast and forced Power to run the dusty outside line through turn 2, and the loss of grip not only thwarted Power's ambitions to pass the #9 but also lost him two positions as Ryan Hunter-Reay and Helio Castroneves streamed past before he could pick up speed again. Also losing out from the compacting of the field was Sebastien Bourdais, who was forced onto pit road after crushing his front wing on the back of Marco Andretti's car.

An overly optimistic lunge by EJ Viso down the inside of Justin Wilson at the hairpin triggered the second caution on lap 7 when the #19 stalled and was left spun around across the track at turn 7, although Dale Coyne Racing car was restarted without losing a lap. The yellow gave Wilson and the select group of cars that had started the race on the problematic hard primary tyres a chance to come in and change to the red-walled options before the restart on lap 10, which saw Will Power successfully recover one of his earlier dropped positions by passing his Penske team mate Helio Castroeneves for fourth.

The Ganassis started pulling away the field with alarming speed and it was probably a relief when a new caution materialised on lap 17 after Bourdais turned Simona de Silvestro around with hefty contact at - inevitably - turn 7. That allowed all the leaders to pit save for Ryan Hunter-Reay who stayed out to assume the lead while Franchitti was back in traffic in sixth place. Power managed to jump ahead of Dixon on pit road, but Dixon quickly reset that when the track went green again on lap 19, at the same time that Charlie Kimball cheekily managed to blast his way past the race leader to put himself back on the lead lap after his incident at the start of the race.

There was soon more incident, with Graham Rahal spinning after being trapped in the middle of a three-wide sandwich through turns 1 and 2 and bounced like a pinball between Marco Andretti and Simon Pagenaud. Despite being hit by AJ Foyt Racing's Takuma Sato, Rahal was able to keep the car running and get back underway without requiring another full course caution. That wasn't the case moments later when JR Hildebrand was spun around by Tony Kanaan in turn 7 on lap 22, and this time Hunter-Reay used the opportunity to come onto pit road as he really should have done under the previous caution. Because of the delay, he now dropped out of the lead and well outside the top ten.

The action continued to be fast and furious at the restart on lap 26. Running in second place behind Justin Wilson - who has assumed the lead after the pit stops thanks to being off-strategy after pitting following his early spin - James Hinchcliffe was tapped into the dirt in turn 2 by contact with Sebastian Saavedra. Hinchcliffe recovered and was able to continue having dropped four positions, and that left Wilson clear at the front with Dixon now in second ahead of Power while polesitter Dario Franchitti had been shuffled back to fourth spot during the stop-start action.

With Newgarden back in the race after his gearbox was repaired on pit road and the AJ Foyt Racing crew still working feverishly on repairing the damaged suspension on Sato's #14 car, Rahal Letterman Lanigan Racing's James Jakes became the first official retirement on lap 28 when the Honda engine on the #16 failed, leaving the Englishman parked in the run-off at turn 9 and triggering a fifth full course caution - already a record number for Sonoma barely a third of the way way, an amazing turnaround from the near caution-free events in the recent past.

Wilson struggled on his ageing tyres at the restart, allowing Dixon to pass him in a bold move around the outside. Wilson soon started losing more positions and finally yielded to the inevitable on lap 37, heading to pit road under green for a new set of reds which dropped him down to 21st on his offset strategy. It mean he was several spots behind his rookie team mate James Davison, who was up 17 positions at this stage having been demoted to the back of the grid for the start following a pre-race unapproved engine change in the #18 car.

Dixon established a lead of around a second over Will Power at the front of the field during the next phase of the race. Dario Franchitti was some four seconds further back down the road, although he had a similar margin in hand over Helio Castroneves, Marco Andretti, Simon Pagenaud and Ryan Briscoe who were running close together in a pack. Power was in for his next pit stop at the end of lap 44, while the Ganassi pair and Helio Castroneves stayed out a lap longer before heading in. The net result was that Dixon exited pit lane right in front of Power and despite being disadvantaged on colder tyres the Kiwi was able to cling onto the position despite all the Australian could do to pressure him into a mistake. In fact it was Power who made the error and strayed wide on his prime tyres, enabling Justin Wilson on the options - and not due to pit again until lap 61 - to move past him for track position, after which Wilson spent the rest of his stint camped on the back of Scott Dixon's car for the race lead.

Shortly after Wilson's pit stop, Josef Newgarden triggered the sixth full course caution of the day by stopping out on track in turn 2. That kicked off a mad scramble to pit lane for the cars that still had to make a final stop, with Dixon and Power coming in at the same time on lap 64. Everything appeared to be going to plan as Dixon pulled out first from his pit stall, which was located immediately behind Will Power's. The Penske right rear tyre changer Travis Law was still carrying the #12's used tyre back to the pit wall when Dixon managed to clip him while making his exit, flipping Law into the air and bowling him into a second Penske crewman, airjack operator Damon Lopez, in the process. It was a nasty incident, with both men shaken but not seriously hurt.

Once the men had been checked out it was time for the question of responsibility and blame. With Dixon getting out in first place ahead of Power it was effectively deciding the race result - with major implications for the championship battle as well. The matter went to the race director, with Ganassi arguing that the tyre changer had been too causal or even being possibly deliberately obstructive in an effort to hold up the rival team's car. That was certainly the view of Scott Dixon himself.

"He walked toward us, on purpose - it's quite blatant," Dixon said after reviewing the incident following the end of the race. "That's a bit of a dick move to be honest ... he just walked into us. I don't know what to say."

I would be very surprised if it was on purpose," responded Power. "I haven't seen the video, so I won't comment on it."

However, IndyCar's own video footage showed that the tyre changer had been firmly inside the Penske pit box at the time of the collision, and in the end the IZOD IndyCar Series rules were clear on the matter. It was the responsibility of the driver of the car to avoid hitting team personnel and equipment on pit lane, and so Dixon was issued with a devastating and highly controversial drive-thru penalty.

"Ultimately, we have a duty to protect everybody in the pit lane," explained Beaux Barfield. "If we have somebody who uses less than great judgement when they leave their pit box and we have an incident, then we have to make a statement by penalising. And we're going to make that call.

"There are a couple of different angles, and clearly the #9 car crosses right into the #12 car's space and that's where the violation occurred. He was in the #12 car's box for a good half-car length."

If nothing else, race control had been consistent throughout the day: everyone who had caused an incident during the race at Sonoma had been handed a similar drive-thru, right back to the very first handed down to Castroneves for spinning Kimball on the opening lap.

All that drama together with the extended period under yellow before the restart on lap 69 meant that several of the cars that had been off-sync were now firmly back in contention, with Justin Wilson the biggest gainer having moved up to second place behind new race leader Will Power once Dixon dropped to 21st after serving his penalty. The rest of the top six was comprised of Franchitti, Pagenaud, Hinchcliffe and Kanaan, with Marco Andretti in seventh ahead of Helio Castroneves, Ryan Hunter-Reay and Sebastian Saavedra. Everyone in the top ten was now on the same option tyres, so it was going to be a straight fight on a level-playing field over the remaining 16 laps of the race.

Hopes that the race would run green from here to the finish were dashed on lap 78 when there was a multiple-car incident at the perennially problematic turn 7. Ryan Briscoe was attempting a pass down the inside of Simona de Silvestro, not realising that Charlie Kimball was turning through the apex ahead of them. Briscoe ended up tapping Kimball into a 180 spin that also shattered his own front wing, but Kimball then made matters far worse by trying to get back underway and only managing to drive straight into the oncoming traffic of Takuma Sato and Ed Carpenter. That resulted in the three of them becoming stuck fast, requiring the seventh caution of the afternoon to separate them and clear the track. This time it was Kimball who was the latest recipient of a freshly minted drive-thru caution in line with race control's ongoing policy of penalising anyone who caused a caution.

That left a four-lap sprint to the finish when the track went green again. Power won the restart battle over Justin Wilson and took off to safe ground, leaving Wilson to settle for second place after he himself pulled clear of Franchitti.

"It is great to be back on the podium again," said Wilson. "Everyone at Dale Coyne Racing has worked so hard to get a result. We've had some ups and downs this year and have run some really good races, but then end up finishing eighth or 10th. So that was a little frustrating earlier this season, but it is nice to get back up here and turn it around a little bit."

It looked for a moment that the race might end under caution when Sebastian Saavedra was crowded off the side of the track going through the Esses and into heavy contact with an outside retaining wall, the #6 continuing to grind along the concrete barrier until it finally hit a tyre wall at the end of the turn 9 run-off that signalled that the car was now sufficiently off-track to allow racing to continue.

With no caution to mix things up one last time, Power was able to seal the deal at the chequered flag and cruise into victory lane ahead of Wilson and Franchitti to claim his first win of the year. "You remember what this is like right?" said Penske manager Tim Cindric over the radio, and it was clear that Power did - and had missed it.

"We've had a lot of hard hits and I'm just happy for all the guys. It's just phenomenal, it's great for our confidence and we're back in our winning ways," he said. "It was good racing. It's hard racing, I can't believe how many restarts, it was crazy. A very good day. I love wine. Especially when you win," as he took a good gulp of the local produce from the vineyards surrounding Sonoma.

Of course, all the questions directed at Power were about the controversial incident on pit road that had made it possible, but it didn't matter to the Aussie: he was finally back to winning ways, and nothing was going to spoil the moment for him. Now all Power wants is for that winning feeling to last all the way to next weekend's street race in Baltimore, so that he can do it all over again; because of course one visit to victory lane is never enough, is it?

See full race results.