Rookie Justin Wilson raced to his first IndyCar Series victory yesterday, edging Helio Castroneves in the Detroit Indy Grand Prix.

Castroneves led for the majority of the road race on the Belle Isle course, but was penalized for blocking Wilson and was forced by rule to relinquish the lead with fewer than 20 laps to go.

Series points leader Scott Dixon finished fifth. That result, coupled with Castroneves' strong showing, means the IndyCar championship will be decided at the final points race at the Chicagoland track next week.

The odds of winning the series title still favor Dixon, who entered the Detroit race 43 points ahead of Castroneves. Dixon needs to finish eighth or better next week to win his second title and first since his rookie year of 2003.

Wilson, an Englishman who started in the race's fourth position and drives the No. 02 car for actor Paul Newman and his Newman/Haas/Lanigan Racing team, had six top-10 finishes entering the race, including a season-best third-place run at Edmonton.

Castroneves, of Brazil, dominated much of race and looked as if he was headed to a second victory in a row, but IndyCar officials ordered Wilson's car to the lead after it was determined the flamboyant Castroneves was blocking on the 72nd lap.

Castroneves and his Team Penske crew were less than pleased with the ruling that sent him into second place.

"We did what we did because it was a pretty easy call," said Brian Barnhart, IndyCar Series president of competition and operations. "He had a tremendous run out of Turn 12, and Helio crossed over almost the entire width of the track to impede the progress of the car behind him."

The scheduled 90-lap race ended after 87 laps when the race hit the 2-hour time limit.

Tony Kanaan, last year's winner at Detroit, finished third. Oriol Servia was fourth.

Kyle Busch was dominant late Saturday night on the 2-mile oval at Auto Club Speedway in Fontana, Calif., leading 144 of the 150 laps to race off with his seventh Nationwide Series victory of the season. Busch easily held off Sprint Cup rival Carl Edwards on two late-race restarts, piling up his record 18th NASCAR victory of the season, including eight in Cup and three in the Truck Series.