SONOMA, Calif. — Helio Castroneves finally broke through for a victory Sunday at Infineon Raceway, winning for the first time in 30 races.

More important, the Team Penske star, frustrated until now with seven runner-up finishes this season, kept alive his hopes for an IndyCar Series championship as points leader Scott Dixon had one of his worst days of the season, finishing 12th.

Dixon saw his lead shrink from a seemingly comfortable 78 points to 43 heading into next week's race at Detroit's Belle Isle, the penultimate race of the season.

Castroneves and teammate Ryan Briscoe started 1-2 and finished the same way, completing an amazing weekend after losing their primary cars in a transporter fire on Wednesday and racing in the Grand Prix of Sonoma in hastily prepared backup cars.

Castroneves was almost delirious with joy as he crossed the finish line, screaming and hollering, "Bring it home, baby."

Nicknamed Spider Man for his fence-climbing victory celebrations, the Brazilian scrambled out of his No. 3 Dallara Honda at the finish line and looked for something to climb. The best he could do was a short fence behind the pits that put him into a crowd of fans, who helped Castroneves celebrate.

Castroneves then sprinted back to his team, joining them in a group hug.

"They kept telling me, 'Push, push, push.' And I was pushing to the limit," Castroneves said. "There was nothing left out there.

"That was fun, a lot of fun. Oh my God, this is awesome. We've been close so often. We never lost faith. This is great for Detroit."

Dixon had a frustrating race.

"We lost a ton of points," he said. "This is a race that's very tough. Unfortunately, we got the bad end of the stick. Hopefully, we'll turn it around next time.

"When you lose 30-whatever (points) today, it makes it a lot easier to come back."

Castroneves, who started from the pole, won this one, his 13th career victory, with a perfect pit strategy and a very strong car.

He gave up the lead on his first stop on lap 17 of the 80-lap event and regained the top spot when the last of the leaders, rookie E.J. Viso, finally pitted on lap 36. By the time Castroneves pitted again on lap 44, he had built a lead of more than 16.5 seconds over Briscoe.

That put the two-time Indianapolis 500 winner right where he wanted to be. After he made the last of his three fuel stops on lap 57, all Castroneves had to do was wait for the drivers ahead of him to make their last stops.

He took over the lead for good on lap 59 when Viso pitted and easily led the rest of the way on the 2.245-mile, 12-turn road course, beating Briscoe to the finish line by 5.29 seconds — about 30 car-lengths.

Tony Kanaan and Den Wheldon, both eliminated from championship contention on Sunday, finished third and fourth, followed by Danica Patrick and Viso.

When Dixon made his second of three stops, also on lap 44, he was third, just behind Briscoe. But the New Zealander came out of that stop deep in the pack and was never in contention again.

"I'm not upset with anybody, particularly. We just did absolutely nothing right," said Dixon, who has a record-tying six wins this season and had only two finishes worse than fourth until Sunday. "Everything we did was wrong."