Californian A.J. Allmendinger passed Tony Kanaan to take the lead at the halfway point of the Indianapolis 500 on Sunday.
Kanaan was second, reigning IndyCar champion Ryan Hunter-Reay was third and Marco Andretti was fourth in a race that featured repeated lead changes.
Before Allmendinger charged to the front, Andretti, Kanaan and pole-sitter Ed Carpenter repeatedly swapped the lead. Carpenter then dropped back to ninth.
Helio Castroneves, one of two drivers trying to win his fourth Indy 500, was running fifth.
The other, defending race winner Dario Franchitti, was struggling. He was running 17th, exactly where he started.The start of the race -- always a nerve-wracking moment as the field squeezes through the first turn -- went smoothly.
But only two laps later JR Hildebrand brought out the first caution of the day when he spun and crashed into the wall between first and second turns. Hildebrand was not hurt.
On Lap 57, Takuma Sato -- the A.J. Foyt Racing driver who had been running eighth -- lost control and spun coming out of Turn 2.
Sato's car wasn't damaged and he continued, but had dropped to 27th. He had worked his way back to 22nd by the halfway point.