Helio Castroneves and Scott Dixon are poised to go head-to-head for victory in the Indianapolis 500 as they lead the field with just 50 laps to run.
Dixon led into the second half of the race, with his Ganassi team-mate Dario Franchitti at close quarters and Will Power third in the first of the Penske cars.
Nelson Philippe caused a caution period when he brushed the wall at Turn 4 while being lapped by a pack of cars. That triggered a round of pitstops in which Franchitti lost time and dropped to 12th place when he almost left his pit bay with the fuel hose still attached.
Vitor Meira had a scary moment when a fuel leak ignited during his pitstop, but the team put out the fire and he was able to rejoin the race in 20th place.
Castroneves moved back up into second place during the pitstops and then shot down the inside of Dixon into Turn 1 to take the lead on the restart.
Power still holds third place, ahead of Dan Wheldon, Townsend Bell and Paul Tracy.