Scott Dixon admitted that he was "just cruising" at times during the final Indy Japan to be held at Motegi - and it certainly looked as though he couldn't have had a better afternoon than he did.

"I have to give a lot of credit to Team Target; they gave me a fantastic car," he said, adding that at points he was just having to manage his fuel conservation to make the mileage. "Great pit stops and fuel strategy, and everything was flawless."

He did come under a strong challenge from Will Power at the start, and only just squeezed the front of Power's #12 at pit exit to retain his lead coming out of the first round of stops, but otherwise it was clear that neither Power nor anyone else on the Motegi road course had anything for Dixon on Sunday afternoon as he ran to his second win here and his 27th IndyCar victory in total.

Dixon's team mate Dario Franchitti was another story, however, and the incident that he sparked on the first restart on lap 26 could prove to be the most decisive moment of the entire championship - especially if it ends up costing Franchitti this year's championship.

An initial caution had come out for Joao Paulo de Oliveira grinding to a halt in turn 12 on lap 22 after a fuel pump failure, shortly after bumping wheels attempting an overly ambitious move down the inside of Takuma Sato. "It's disappointing to retire as one of my goals for my first race was to finish the race but the experience overall was quite valuable," said the 2010 Formula Nippon champion who was making his IndyCar race d?but. "I think we were doing a good race and looking good for a top-10 finish ... That's racing."

At the restart Dario Franchitti tried a rash, half-hearted move down the inside of Ryan Briscoe into turn 1, and there was contact: Briscoe spun, catching Graham Rahal in the process and also blocking the track for Franchitti, who came to a standstill while Charlie Kimball managed to take avoiding action into the dirt rather than ploughing into the stationary cars and making a bad situation worse. A new full course caution came out straight away.

All four cars were able to continue, but they were now at the back of the lead lap. Franchitti also needed to pit for a new front wing, and was then also penalised for causing an avoidable accident. He didn't dispute that the penalty was earned.

"The incident was totally my mistake, totally my mistake ... I made risky move on the restart," he said. "It was a stupid move on my part ... I thought there was a gap and Ryan was going wide on the entry and that was that. It was just a stupid move."

He added that he was already busy making his apologies to the other three drivers whose races he had also affected, as well as to team boss Chip Ganassi who had appeared distinctly unhappy when interviewed during the race over how Dario's actions had wrecked three-quarters of the team's cars' hopes.

"I apologized to Graham and I apologized to Chip, Briscoe and Charlie I will apologize to when I see them," said Dario. "I own up to the mistake and Chip is right to be critical. It was a stupid move, and I shouldn't have done it."

Given that this season has been dominated by controversy over decisions from race control, Motegi was no different: eyebrows were raised at the applied penalty which put Franchitti to the back of the lead lap rather than the usual drive-thru penalty once the track went green. Given that Franchitti was already pretty near the back anyway, the applied penalty did him little harm - whereas a drive-thru would have dropped him even further back in track position.

Once the race got back underway, Dario spent the rest of the race working his way up from the back, finding some cars easier to overtake - such as Hideki Mutoh on lap 36 - than others. Giorgio Pantano made it clear he wasn't going to make things easy when he cut off Dario's attempt to pass on the next lap, only to then drift off into the dirt and lose momentum which gave Dario the position a few minutes later anyway.

Franchitti was also helped by a third and final full course caution that came out on lap 58, when Sebastien Bourdais delivered a forceful hit on the rear left wheel of Ryan Hunter-Reay's #28 on the entry to turn 4. Hunter-Reay was sent off into the sandtrap where he was beached, and the caution came out to allow the crane to move into action.

Surprisingly, Bourdais received no penalty for the accident despite the superficial similarity to the earlier Franchitti/Briscoe collision. "The reason we deemed it a racing incident is because Bourdais made a mistake coming off of Turn 2," said race steward Al Unser Jr. "Ryan's choice to go on driver's right, and then didn't give him enough room going around Turn 3."

The restart proved eventful: the first attempt at taking the green was foiled by a strangely unprepared and out of position Will Power; the second attempt proved successful at going green, but then KV Racing Technology team mates Takuma Sato and EJ Viso made contact - leaving Viso spun off the track - while Ryan Briscoe also went off-road and Vitor Meira likewise ended up beached on the side of the track.

None of those were in a dangerous enough position to force a full course caution, and given that there were only a couple of laps remaining at this point, race control made the decision to handle it under local waved yellows instead and allow the race to end under green.

Helio Castroneves was seen to overtake JR Hildebrand for seventh place under one of these local waved yellows on the final lap, and was duly penalised for the transgression - which meant being put to the back of the lead lap in the final positions, leaving him mired in 22nd. He wasn't happy when he found out.

"I am very disappointed in the result and the decision to penalize us at the end," he said afterwards. "I have said it before: the decisions by Race Control have been very inconsistent, this season especially, and I think today was just another example. I am really upset about it and I think it is very unfortunate for the fans and my fellow drivers."

It was a sad end to Castroneves' day, which had also started with drama when he tried a move on Ryan Briscoe and Graham Rahal who were battling in front of him: that make it three-wide into turn 1 at the start, and Briscoe and Rahal ended up running deep which left Castroneves no where to go except into the sand trap, costing him a huge number of positions after he rally crossed back to the tarmac in 21st position.

While it might have been a disappointing day for two thirds of the Penske operation, there was no mistaking the big smile of relief on Will Power's face as he collected the Mario Andretti Trophy for winning the ten-race road course part of the 2011 IndyCar championship for a second straight year.

"It's an honour to win the Mario Andretti Road Course award again, I have such respect for Mario and all he's accomplished," said Power, who was happy enough with second today. "We tried everything we possibly could to get Dixon, but he was very aggressive and he really deserved the win."

Despite the obvious frustration of not being a match for Dixon at Motegi, Power was still streets ahead of the rest of the field for most of the afternoon and he finished almost 5s ahead of Marco Andretti, Alex Tagliani and Oriol Servia (who had all made up ground in the pit stops) despite only two laps of green flag running at the end.

Will had badly needed to come out of the final road race of the season with this points lead over Franchitti (who theoretically has a slight edge in the remaining oval races) if he is to have a strong chance of adding the overall drivers' title to the Mario Andretti Road Course award.

"It was a good day for us points-wise in the championship, but I'm really not worried about points right now," said Power."I just need to keep finishing in front of the #10 car the rest of the way and we'll be fine. We'll keep chipping away like we have been."

Franchitti - who ended up finishing in eighth position after running damage control, and benefiting from the incidents at the final restart and the penalty that was applied post-race to Castroneves - was remaining philosophical about his own chances.

"We still have it all to play for, but I keep making it more difficult ... That was a mistake today. Shouldn't have made it," he admitted. "If you win or if you lose, you always look at the championship as a whole. Today; Loudon; Texas; Indy; and on and on. You always look at these things, but Will can do the same with his races."

The poor qualifying performance and the rash move that cost him a strong showing at Motegi may be worrying signs that the reigning champion is feeling the pressure of the title fight, but he'll now have two weeks to regroup and face the last two races of the season. He'll be hoping that the move to ovals at Kentucky and Las Vegas will hand the momentum back to the #10 and that he'll emerge victorious.

Right now, the championship is genuinely too close to call.

Full race results available.