Ryan Briscoe edged Scott Dixon by 0.0077secs to win the PEAK Antifreeze & Motor Oil Indy 300 at Chicagoland Speedway, increasing his advantage at the top of the IndyCar Series point standings in the process.

Starting from the pole, the Australian was a factor all night, but was forced to go head-to-head with his antipodean rival after a late-race caution, ironically caused by a mechanical failure that sent Penske team-mate Helio Castroneves into the wall on lap 185.

The lap 191 restart contributed to the late-race drama as Briscoe and Dixon swapped the lead four times over the final nine laps, and ran no more than 0.08secs apart throughout the denouement. Holding the outside line, the Australian only got the edge on the dash for the flag, before crossing the line a fraction ahead of his rival - and uncertain of his victory until some time after the flag had dropped. The outcome had echoes of last season's Chicagoland finale, where Dixon thought he had won, before the nod was given to Castroneves.

The victory, the third of the season for Briscoe, was the fourth-closest finish in IndyCar Series history - the equivalent of 28.5 inches - and helped the Team Penske driver take a 25-point lead - over Dixon's Ganassi team-mate Dario Franchitti - to the next round, in Japan, next month.

"We've got to stay focused," he insisted, "The Target cars are going to be there in Motegi and Homestead, so we just have to stay focused. We've had good cars on all the mile-and-half ovals this year. We've just got to keep it together. We had a couple of mistakes tonight but were able to come back. We've just have to try to avoid those situations."

For Dixon, it was a fourth near miss at Chicagoland Speedway in as many years, and the Kiwi dropped 33 points back from Briscoe with two races remaining.

"We've all seen this movie several times," the reigning champion sighed, "Unfortunately, at Chicago, we just keep finishing second.

"The whole night, I think we drove a better race - the guys on the team did a fantastic job, the pit stops were flawless. We launched out there a few times but we just didn't have the speed. Our mile-and-half dominance, that we seemed to have last year on the Target team, has just really been affected. We need to play catch up with Penske. They clearly are a lot faster than us. That's all I had."

The restart bunched the field to the extent that the leading 16 cars were all within a second of Briscoe at the finish. Mario Moraes, fast all night in the #5 KV Racing Technology entry, finished a career-best third - just 0.0609secs from victory - after running sixth on lap 198.