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."