Helio Castroneves

HOUSTON -- Helio Castroneves has walked away disappointed from IndyCar Series championship hunts in seasons past. But none might have hurt more than when the three-time Indianapolis 500 winner walked away from his disabled car on pit lane early in Race 2 of the Shell and Pennzoil Grand Prix of Houston.

Castroneves, who took the outright points lead with a victory at Texas Motor Speedway and held it for nine races over four months, entered the third doubleheader of the season with a 49-point advantage over two-time series champion Scott Dixon and as the only driver to complete all 2,003 laps.

After qualifying a season-low 21st and finishing 18th in Race 1, combined with Dixon's victory, Castroneves' lead was sliced to eight. A shifter issue early in Race 1 required repairs on pit lane that dropped Castroneves nine laps down.

In Race 2, a broken gearbox housing left the No. 3 entry stranded in Turn 6 of the 1.634-mile, 10-turn circuit carved out of parking lots abutting Reliant Stadium and the Astrodome on Lap 11 and significantly impacted Castroneves' hopes of securing his first series title. Team owner Roger Penske said the car "bottoming out" after going over a bump broke the gearbox.

The crew returned the car to its temporary garage area to replace the gearbox and rear suspension, and Castroneves rejoined the race on Lap 47 (36 laps down to race leader and teammate Will Power) and he finished 23rd. Dixon takes a 25-point lead into the finale.

“Well, obviously this is not how we wanted our weekend to go," said Castroneves, who had a streak of 12 consecutive top-10 finishes end in Race 1. "We started the race strong in the Shell Pennzoil Chevy and then I just couldn’t shift the car. It was a very helpless feeling.

"I have to say, what an incredible job by my guys to fix the damage. The Shell and Pennzoil crew basically replaced the whole rear of the car and we were at least able to get back out on track and pick up another position. I feel bad for the team because they’ve worked so hard to get us in a position to win this championship.

"And there is still a lot of racing left. We know we have a strong car in Fontana."

The MAVTV 500 INDYCAR World Championships at the 2-mile Auto Club Speedway oval in Fontana, Calif., is Oct. 19. Castroneves was among 23 drivers who tested at the venue Sept. 24 in preparation for the 250-lap twilight race on NBC Sports Network.

"The good news is we had a test there and it was extremely good," Castroneves continued. "It's going to be a heck of a race."

Power went on to win the race, his second of the season.

"Obviously, with Will out there battling with the 9 car and taking some points away was key for us," Penske said. "So he got his job done. The racing isn't over."

The season finale will decide the series championship for the eighth consecutive season. In 2008, Castroneves  trailed Dixon by 30 points entering the finale at Chicagoland Speedway. He won the race by .0033 of a second -- the second-closest race in IndyCar Series history -- over Dixon, who earned the title by 17 points.

The standings heading into the final race the past five seasons:

2008 -- Dixon 606  Castroneves 576
2009 -- Dixon 570  Franchitti 565
2010 -- Power 587  Franchitti 575
2011 -- Power 542  Franchitti 531
2012 -- Power 453  Hunter-Reay 436