The IndyCar series heads west for its final two races to determine the series championship, with the title battle likely to be decided by
After winning Sunday's race in Milwaukee, Power has a 39-point lead over second-place Castroneves in the Verizon
Power, who has finished second in the title standings three times, would appear to be the favorite to capture his first championship.
The series' next race is Sunday on the curvy Sonoma Raceway road course in California's wine country, where Power has won three of the last four years, including in 2013.
Then the series has its season finale -- a night race Aug. 30 -- at the 2-mile Auto Club Speedway oval in Fontana where speeds top 200 mph. Power also won that race last year.
But there's a wrinkle this season. IndyCar is now awarding double championship points at its 500-mile races, which includes the Fontana event.
IndyCar normally awards points on a sliding scale depending on a driver's finish, starting with 50 points to the winner (excluding bonus points for winning the pole, leading the most laps and so forth).
But at Fontana, the points scale will start with 100 for the winner, which could make a difference in who emerges as the champion.
"We are not giving up at all - there are two races to go with the big one at Auto Club Speedway in Fontana paying double points," Castroneves said in notes released by his team. "Still a lot of racing left."
Power, in turn, said "we're going to keep our head down, don't think of points and execute" in hope of winning the championship.