A caution-free 75-lap Edmonton Indy nonetheless managed to serve up entertaining on-track battles and culminated in a gripping 16-lap stand-off between Helio Castroneves and Takuma Sato for the race win, with Helio able to hold on to the top spot thanks to some crucial early hoarding of his push-to-pass power boost to claim his first victory in the event and make up in part for his infamous 'stolen win' of 2010.

Dario Franchitti started from pole position alongside Ryan Briscoe, after five engine change penalties included pole winner Ryan Hunter-Reay (who ended up starting from 11th) and leading title contenders Will Power (demoted to 17th) and Scott Dixon (down to 18th.)

In fact it was third-place starter Alex Tagliani who made the first move as the green flag came out, locking onto Franchitti's tail into turn 1 leaving Briscoe hung out to dry on the outside line and having to lift off to avoid thumping into the tyre wall. That forced Briscoe to wait to fall in behind Takuma Sato and Helio Castroneves, a fall of three places in that opening corner.

Next time down the main straightaway, Tagliani wanted still more: he applied his push-to-pass boost in a textbook overtake move on Franchitti and started to pull away from the field, to the ecstatic cheers of the Canadian crowd supporting one of their tho local heroes in the race.

Other drivers were also making some good early tactical use of the push-to-pass, which allowed drivers to access 120 seconds of additional power boost over the course of the race. Will Power used it sparingly at the start of lap 4 to scrape past Josef Newgarden for fourth place, Graham Rahal slipped past Rubens Barrichello for sixth on lap 10 and Justin Wilson made a nice move on Simon Pagenaud for eighth right behind them. Pagenaud lost another spot to Ryan Hunter-Reay next time around, again with the help of the boost button.

But things did not always go to plan on the push-to-pass front: James Hinchcliffe's attempt to deploy push-to-pass to get around Pagenaud into turn 1 on lap 15 fell short, and when he tried again next time he ended up locking up and running wide, haemorrhaging positions in the process. The chasing cars got caught out by this sudden development, and Will Power struggled to make his own way through the corner - even brushing the wall with his right side tyres as the #12 struggled to put the power down again.

It was soon apparent that almost everyone was on a two-stop strategy which required strict adherence to a fuel conservation strategy, especially when no cautions materialised for the entire 75-lap length of the race. JR Hildebrand was an early visitor to pit lane in the opening laps for a new front wing, but otherwise only Tony Kanaan tried to go off-sync with his strategy by converting to a three-stopper by coming in early on lap 12 when it was clear he was making little progress through the field by conventional methods. The lack of cautions meant that Plan B fared little better, however, and Kanaan would slot it out to an 18th-place finish by the end.

The rest of the field cycled through the pit stops at around the one-third race distance mark, with the four leaders - Tagliani, Franchitti, Sato and Castroneves - in on lap 26. They all came out in the same order they entered, but when they returned to the track Castroneves quickly passed Sato and Franchitti clearly had similar ideas about making a move on Tagliani, feeling that the Canadian had spent quite long enough in the lead by now.

It didn't work out that way for him: try as he might with the push-to-pass, Franchitti failed to get around the #98 - and in trying to force the matter over the following corners he left the inside line vulnerable to an opportunistic strike by Castroneves who surged through to second place in turn 5.

That left Franchitti in the sights of Sato, with whom he famously tangled on the last lap of the Indianapolis 500 in May. This week, it was Sato who got his revenge for that clash when he pulled off a picture-perfect pass on Franchitti at the start of lap 37, Franchitti seemingly having problems activating his push-to-pass boost as a defensive measure. Despite a reboot of the system apparently fixing the problem, Franchitti was conspicuously not able to match the top pace of the cars around him for the rest of the afternoon, soon succumbing to a move from his junior team mate Graham Rahal and finally having to settle for a somewhat underwhelming sixth place by the chequered flag.

"Not a good day," admitted Franchitti afterwards. "We missed something on the setup. The Target car was not bad on new tyres but we had a massive imbalance there. I'm pretty sure I know what we missed so we'll gather it up and head to Mid-Ohio in a few weeks."

Tagliani continued to lead comfortably ahead of Castoneves through to the next round of pit stops around lap 50. Castroneves pitted first and had the perfect stop and a blistering outlap, while Tagliani's was slightly slower and as a result he emerged back onto the track just behind the Penske car. Moreover, the final set of mostly-scrubbed tyres didn't seem to suit the Canadian and his performance fell off steeply, making it easy for Sato to take second place from him shortly after with a beautifully smooth move down the inside of the hairpin.

"When we put on the second set of tyres that were a little old, I don't think we had as much speed as the other guys and it was hurting us," admitted Tagliani, but preferring to look on the bright side at the huge strides the Bryan Herta Autosport had made this week: "I'm very, very proud of the team. Everybody did fantastic. We had a pretty good car early in the race. It was the perfect timing to save fuel and the balance of the car was very good."

He added, "We're competitive and I could not ask for more. If we keep doing it every race, then I'll be happy."

Before that round of pit stops, Will Power had already moved up to sixth place by a combination of patience, prudent applications of push-to-pass, and a top-notch pit strategy made possible by his ability to stretch a tank of gas further than anyone else. He gained two more positions by passing Rahal and Franchitti with his final visit to pit lane, although Penske Racing president Tim Cindric admitted that they had intentionally cut it fine on the fuel to gain those two spots and that were relying on Power being able to make the short-fill tactic pay off. He did, and by the end was able to gain another position by passing the waning Tagliani to finish in third position ahead of Graham Rahal.

"It was definitely an enjoyable drive, [but] I couldn't catch those guys at the end," he admitted. "I think if we started 17th and there was going to be no yellows, and we thought we'd end up third, we'd take that for sure. Man, good day. We're definitely tightening up the championship."

With the field finally getting string out and the positions now looking set, the focus turned to the increasingly tense battle for the lead between Castroneves and Sato: Takuma appeared to have the raw pace and was all over the back of the #3 car, but Helio had eschewed any use of his push-to-pass button in the first half of the race and that gave him a bucket full of boosts to play with now. Anytime Sato got a run and tried to apply his own push-to-pass, Castroneves could parry it.

As the laps counted down, it was clear that it would take a trademark Sato banzai move to make anything happen. But Sato's car owner Bobby Rahal was onto his driver over the team radio, coaching him through the corners and imploring the Japanese former F1 driver to bring the car home in one piece and that finishing second was infinitely better than risking it all and not finishing.

Rahal also came up with the quote of the day as he watched Castroneves steadfastly defend his lead over those closing laps: "Helio is tough," Rahal told TV reporters. "He starts blocking when he picks up his rental car at the airport."

Sato got the message about the finish being more important than the win, and as his push-to-pass expired on the final lap he conceded defeat and cruised over the finish line 0.8367s behind a jubilant race-winner.

"It's my second win here," quipped Castroneves afterwards. "Legitimate now!" he laughed, adding: "It's fantastic ... I think this place owed us a little bit."

For Helio, this was more than just a welcome return to victory lane for the second time in 2012, it was little short of redemption for a past wrong done to him. He's been runner-up here three times, and in 2010 thought he'd won the race only to find he'd been penalised for blocking through the final corner and dumped back down to 10th place, which saw the demonstrative Brazilian express his displeasure in the plainest possible way to the nearest IndyCar official he could (literally) lay his hands on.

But that was all in the past, after his victory today: and he wasted no time in climbing up the nearest catchfence he could find to deliver his trademark 'Spider-Man' celebration, to the delight of the crowd which - if it couldn't have a Canadian on victory lane - was happy to settle for one of the personable and excitable characters in the IndyCar paddock.

"He did a great job," said team owner Roger Penske. "It's a credit to the team, obviously when you see the competitive edge that's out there with Takuma and all of the other drivers. You can't make a mistake. The fuel economy was important. Today the Chevy engines ran great. I take my hat off to Helio. It was a tough race."

Sato himself said that he's really enjoyed his epic battle with Castroneves: "I would have enjoyed it a little more if I could overtake him, but you know we were not quite there. He did obviously, a great job, made no mistakes at all," he said. "I knew he had a little bit longer sequence of the push to pass. I used it bit by bit, but also he's reacting all the time the last few laps and he used every single straight."

The race had indeed ended up running all 75 laps without a single caution, and only two cars were listed as retiring: James Jakes exited just over halfway through with a broken damper on the left rear of the Dale Coyne Racing car, while Oriol Servia's Panther/DRR car suffered a mechanical problem in the pits which saw it struggle to get back underway which put him five laps down and ultimately led to retirement on lap 66.

Scott Dixon and Simon Pagenaud both suffered early intermittent problems with their Honda engines which fortunately cleared up with some pit lane attention."

"We had a problem at the start within the first five laps," explained Dixon, who managed to recover to tenth place despite the issues and his lowly starting position. "Whenever I went into the braking zones the engine would go into neutral. We had a little problem with the anti-stall function in practice, but then in the race it just kept doing it. That really hurt us especially because the race didn't have any yellows."

"We were missing a lot of straight-line speed," contributed Paganeud. "We probably had the best car in the infield portion, but it was frustrating because we were losing a lot of ground in the straights. With no yellow flags, we were kind of in a zone."

Pagenaud's race ended up in frustration in 20th place after he was run into by Charlie Kimball on the penultimate lap: "We we're hanging in there and still could have scored a 13th place if Kimball wouldn't have made a stupid move. He used me to make his corner. I'm very disappointed in that. It's not very smart."

Kimball received a post-race time penalty in lieu of the drive-thru he would have received otherwise for causing a collision. He had been lucky to escape censure earlier on the race after tangling with Marco Andretti on lap 21, at one point seemingly jinking right and forcing Marco across the forbidden pit lane blend line in order to complete his own pass on the #26 into turn 1.

Sebastien Bourdais did have a drive-thru penalty on lap 29 for blocking, and Josef Newgarden was similarly penalised on lap 52 for speeding on pit lane, but the most controversial call came after Will Power appeared to chop in front of Ryan Hunter-Reay as he emerged from the pit lane and cut across the blend line into the apex of turn 1. Hunter-Reay was furious about the move over the team radio and still fuming after the race about race control's decision not to levy a penalty on Power.

"I expected it to be called, I expected him to be thrown off, but it didn't happen," he said afterwards.

But more crucially, Hunter-Reay had been unable to match Power's ability at working his way through the field over the course of the entire race: where Power made up 14 places over the 75 laps, Hunter-Reay managed to climb only four places from where he started.

"We just needed a yellow. We needed something ... anything," he admitted. "To take an engine penalty on a day like today - at a track with long straights - we expected yellows. Maybe lots of them, but we just didn't get 'em.

"It's strange, with all of the marbles we have out there, you'd expect someone to go off or spin or something," he added. "I was praying for a caution and it didn't come. Had we had a yellow, I think I could have gained spots on the restart."

His seventh place finish has a significant impact in the points standings: while he is still out in front his lead has been pared back: Hunter-Reay has only 23pts over Helio Castroneves who has edged in front of his Penske team mate Will Power by just three points. Scott Dixon and James Hinchcliffe are still just about hanging on, but are at risk of losing touch with the leaders with only four races remaining in the 2012 IZOD IndyCar Series season which concludes at Fontana in mid-September.

"It's going to be nail-biting until the end," agreed Hunter-Reay. "It'll be a heckuva shootout at Fontana, and I'll bet it'll come down to a fight between three cars."

Everyone further back - including reigning champion Dario Franchitti - might not be mathematically out of the running just yet, but they will know that their prospects are very much dimmed as the season enters its final leg.

Full Edmonton Indy race results available.