Scott Dixon passed Mike Conway with three laps remaining to win the IndyCar Grand Prix of Sonoma while Will Power stretched his season points lead despite a risky late move.
New Zealand's Dixon, the defending series season points champion, won his 35th IndyCar triumph on Sunday to match Bobby Unser for fifth on the all-time list.
Aussie Power attempted a tight pass on Britain's Justin Wilson in the final turns of the last lap but was penalized one spot to make the move all for nought.
"I was going for more," Power said. "It looked like an easier move. Justin looked like he was struggling. But it got three-wide through there."
Power stretched his point total to 626 and his lead to 51 points over Brazilian teammate Helio Castroneves entering next Saturday's final race of the season at Fontana, California.
The oval event pays double points, meaning that France's Simon Pagenaud, in third at 81 points adrift, is also still in the season title hunt.
American race leader Graham Rahal was forced to the pits for fuel with just over three laps remaining and Dixon made an inside move past Conway to seize the lead seconds later.
Dixon pulled away to the finish over the 2.385-mile (3.83-kilometer) road course circuit while Britain's Conway ran out of fuel and barely crossed the line before rolling to a stop, allowing American Ryan Hunter-Reay to finish second with Pagenaud third.
"It was tough," Dixon said. "There were so many strategies going on. I didn't know who could make it and who couldn't.
"So excited. This is big for our team. We had a rat's year so far but today our strategy was perfect."
The race went on despite a 6.0-magnitude earthquake that rocked the area early Sunday, the largest earthquake to strike the region in 25 years.
Power finished 10th, being moved back one spot after passing in the last turn under a caution flag brought out when Conway ran out of gas at the line.
"That was a hairy last corner," Power admitted. "I just saw the opportunity for points and I went for it. That's racing."
Power promised he would not compromise in the finale even though failing to finish would likely be the only way he could stumble out of winning his first series season crown.
"Head down like we have been," Power vowed. "That's all."
Source: AFP