Team Penske's Ryan Briscoe denied Ed Carpenter a maiden IndyCar Series victory by 0.0162secs after duelling with the outsider over the final laps of the Kentucky Indy 300.

Carpenter, an oval specialist who struggles to repeat his form on road and street courses, bounced back after disappointing outings in Toronto and Edmonton to be a surprise candidate for victory on the Sparta oval but, despite having more of the recently-introduced 'push-to-pass' system left in the bank, could not fend Briscoe off forever and lost out on the run to the line as wheel-to-wheel action returned to the Indy Racing League.

Briscoe had been a contender all evening, moving up from an enforced second row start - after qualifying was cancelled due to 'weepers' - to challenge points leader Scott Dixon almost from the start. The pair swapped placed both on track and in the pit-lane, before Dixon dropped back in the final stint, leaving Briscoe to chase down Carpenter, who had assumed the lead after not pitting under the one and only yellow, for debris on lap 123, and then taking fuel only at his final stop.

The Australian first had to overcome a resurgent Tony Kanaan before he could reach Carpenter but, once on the shoulder of the Vision Racing driver, ran side-by-side with him to the flag. Despite holding the outside line - and coming close to banging wheels and sidepods with his rival - Briscoe made the most of the aerodynamic changes introduced for each oval from Kentucky onwards to inch ahead at the stripe. The gap between the cars was still only the eleventh closest finish in IndyCar history.

"Now I know how Sam Hornish Jr used to feel when he would win all of those races on the outside," Briscoe bubbled, "I'm pretty happy to get another one for Team Penske - I just wanted to keep doing what I had been doing.

"Ed would get a little bit in front of me in the middle of turns three and four but, with my momentum on the outside, I was able to edge him down the backstraight. I would time my 'push-to-pass' button so I would get the extra power through three and four.

"It was getting tougher and tougher, and I was just jumping in my seat trying to get in front of him across the finish line. It just worked out perfectly."

With the satellite forecasts suggeting impending rain, Carpenter tried everything he knew to keep his rival at bay, but Briscoe had just enough to break Vision Racing hearts for a second time, having pushed Ryan Hunter-Reay into second in St Petersburg.

"Once we cycled through the lead on that last stop, I was ready for rain or whatever," Carpenter admitted, "I was just trying to run as hard as I could and stay in front. It's been a tough year, and I was hoping this was going to be a break-out race, to try to get our team turned around for the rest of the season and we did that."

Kanaan defied the burns he sustained in last weekend's pit-lane fire in Edmonton to be a contender for victory until the final few laps. Admitting that he and the Andretti Green team had come up short on its choice of gearing, the Brazilian was unable to use the 'push-to-pass' in the closing stages, and had to settle for a close third, just 0.15secs back of the lead pair at the chequered flag, but was enthusiastic about the technical changes made to improve racing on the ovals.

"It was a helluva race," the veteran enthused, "It was pretty much raced clean. The people came here to see a photo finish and we did it. I've got to thank the [Indy Racing] League, Brian Barnhart, all the officials and the guys that came up with this package - and for the 'push-to-pass'. Firestone did a great job to. I can still hear the fans, so I want to thank them for coming. The old IRL is back. We'll have some exciting races on the superspeedways again."

Fellow countryman Helio Castroneves could have been in the mix at the end, and could have helped Briscoe take a more comfortable win, had he not had to get out of the throttle as the #3 Penske car washed wide while running neck-and-neck with Kanaan. Castroneves recovered from the moment in enough time to keep fourth spot, with fifth-placed Graham Rahal nearly another half second adrift at the line.

"I got a little greedy towards the end, tried to help my team-mate so we could do a 1-2 finish - but, man, I went way high and then I started coming back again," HCN revealed, "I was just pushing him so he could be over Ed and then I would be on the outside and it would be a fantastic finish. I still had quite a lot of 'push-to-pass' left."

Against expectations - and contrary to what the early stages suggested at Kentucky - Rahal came home ahead of both Ganassi cars. Although Dario Franchitti faded from his front row spot as his car pushed incessently towards the wall, Dixon's demise was more surprising, as the reigning series champion had been in the top two until the final round of fuel and tyre stops. After nearly jumping the restart and having to slot back into the pack, however, he dropped well away from the lead battle, and eventually came hom seventh - one place behind team-mate Franchitti.

Danica Patrick, Will Power and Marco Andretti rounded out the top ten, with Dan Wheldon, Sarah Fisher and Hideki Mutoh completing the list of unlapped runners.

The lead group should have included Mario Moraes, who found his KVRT car handling and running like a dream in the early stages. The Brazilian's day was ruined, however, when the Dreyer & Reinbold team released Mike Conway into his path at the first round of stops. The contact was enough to turn Moraes around and seriously damage the front of Conway's car, while Ryan Hunter-Reay found himseld confined to his pit stall while the chaos was sorted out. RH-R was evntually classified 14th, with Conway and Moraes 17th and 18th respectively after rejoining - and, in thee Briton's case, returning the pits across the grass infield following an incident.

Fellow Briton Justin Wilson was one of only three retirements - joining Jaques Lazier and Tomas Scheckter - after his Dale coyne car developed a problem at its rear.