HOUSTON (AP) — Scott Dixon made the opening race of the Houston Grand Prix a Penske Racing nightmare, grabbing a series-best fourth victory while slicing a huge chunk off Helio Castroneves' lead in the championship race.

Dixon, who entered Saturday's race trailing Castroneves by 49 points, cut his deficit to eight points heading into Sunday. A sweep of the doubleheader through Reliant Park would put Dixon in control headed into the Oct. 19 finale at Fontana, Calif.

"I hope they are worried, man. That's a 41-point turnaround," he said. "Hopefully, we can have another good race (Sunday). It would be nice to be in the lead going into Fontana. To have a little bit of a buffer would be really nice."

It was the 33rd win of Dixon's career, and one more would tie him with Al Unser Jr. for sixth on the IndyCar list.

Dixon was aided by the first mechanical problem of the season for Castroneves, who had been the only driver to complete every lap this year entering the race. But a mechanical problem just 22 laps in Saturday sent him to pit road.

The Brazilian sat inside his car under a sweltering Texas sun as his crew worked feverishly to replace his gearbox. It took nine laps before Castroneves got back on track, and he wound up 18th.

He was surprisingly upbeat after the race.

"We are still leading," he shrugged. "It's a shame. Those things are outside of our control. I wasn't sure they were going to be able to fix it and when they did, I just went out there and tried to learn the track as best I could. I changed my mode to 'What can I do to learn for race No. 2?' I wasn't even thinking about that I was out of this race. We'll try to recoup tomorrow what we lost."

It was a worst case scenario for the Penske team when a slow pit stop for Will Power allowed Dixon to take the lead.

"It was very disappointing with not being able to keep the lead in the second half of the race," said Power, who wound up 12th because of an ill-timed yellow flag.

The Chip Ganassi Racing driver cruised to a trouble-free race after back-to-back controversies at Sonoma and Baltimore that began with incidents involving Power.

Dixon angrily complained about IndyCar race control after both races, and was fined $30,000 last month by IndyCar for calling for race director Beaux Barfield to be fired and railing against the series' inconsistency. He noted Saturday was incident free.

"It's nice to not have a penalty today," Dixon said during the podium presentation, "maybe I should dedicate this win to Mr. Beaux Barfield."

Simona de Silvestro finished a career-best second to earn her first IndyCar podium in her 63rd start. Justin Wilson was third in his fourth podium finish of the season.

"Well, finally. We've been waiting for this for a long time," said de Silvestro, who was fifth at Baltimore in IndyCar's last race.

Castroneves said he was pulling for de Silvestro after his issue.

"I was looking and I was cheering for Will and I was cheering for Simona, because there was nothing I could do but cheer," said Castroneves, who also praised Dixon. "He did not put a wheel wrong and that's exactly the championship way."

IndyCar's first race in Houston since 2007 has been plagued by a bump in the first turn that was not discovered until cars hit the track for the first time Friday. Because the promoter could not start building the course until after the Houston Texans' game on Sunday, IndyCar had no access to the track and a build usually done over several weeks was completed over several days.

Qualifying was postponed Friday and IndyCar used a chicane of tires at the bump so drivers could still practice, and crews used a grinder on the surface all night to try to smooth it down. It was still rough, though, and IndyCar decided it could only do single-file restarts for the two races because of the issue.

Then the race itself got off to a bizarre beginning when James Hinchcliffe stalled on IndyCar's standing start.

He was lined up in the third row, and cars had to dart around him to avoid a massive collision. Ed Carpenter didn't miss Hinchcliffe, though, and ran into the back of his stalled car. Hinchcliffe walked briskly back to his Andretti Autosport pit stand and tried to compose himself.

"Man, I'm furious. I know what happened, I don't want to talk about what happened," he said. "I'm mad. I'm out of the race. I don't want to get into it here. We've had troubles all weekend with something electrical on the car. We finally got it sorted for qualifying. We were ready, it was go time, and we didn't go.

"We'll regroup. We'll get 'em tomorrow. I'll calm down."

Carpenter had to sit and watch while his team worked furiously to repair his car. His team transporter was in a fire in Arizona while returning from last week's test in California and the backup car suffered smoke damage.

"I was following the cars in front of me, some dust was flying, one of the cars I was following dodged to one side and I tried to dodge to the inside but I clipped Hinch's car," Carpenter said. "It was tough to see with the other cars right in front of me. Just a tough break."

The race immediately went to caution with pole-sitter Takuma Sato out front with team owner A.J. Foyt in attendance for the first time since he underwent hip replacement surgery July 1. But Foyt, serving as the grand marshal for his hometown race, wasn't able to celebrate for long: Sato had to pit on lap seven with a flat tire.

That turned the lead over to Power with Dixon right behind him. The two have had issues in IndyCar's last two races, and it's been magnified because Dixon is racing Power's teammate for the championship.

The race took a sudden turn when Castroneves headed to pit road on lap 22 with a gearbox problem. And it went from bad to worse for Penske moments later during green-flag pit stops. Dixon headed in before Power and his Ganassi crew got him out in 7.4 seconds.

Power then made his stop as Dixon was racing around the course, trying desperately to circle the track before Power exited pit road. Dixon did it — in part because the Penske crew needed 9.2 seconds on a troublesome stop for Power.

With Dixon now out front, he had control of the race and the points lead in his sight.