Ryan Briscoe also had a strong showing, as he finished fourth in the No. 6 Team Penske Dallara/Honda. Briscoe led 32 laps and battled among the leaders for much of the race before posting his seventh top-five result of 2010.
In the pivotal sequence of the event, Castroneves emerged with the race lead following the final pit stop of the day under caution on Lap 150. Briscoe came out of the pits in third place behind Franchitti while the No. 12 crew had their best stop of the race to move Power up to the fourth position. Briscoe tried to get by Franchitti for second place after the Lap 167 race restart but Franchitti drove down low on the track to prevent the pass. Briscoe had to back off and lost momentum as Power was able to get by his teammate to claim third place.
"The finish wasn't what we were hoping for, but we're happy that Helio won and Will still leads the championship," said Briscoe. "It was really exciting out there today. I was racing hard with Dario and it was awesome. We raced each other hard and clean. There are not too many guys out there that I feel comfortable racing with the way we did. Congratulations to Helio and Team Penske for bringing home the victory. The No. 6 car was great today, although our result was a bit unfortunate. We made a run on Dario on the last restart and he took me down to the white line and I had to back out of the throttle to avoid wrecking. Will was able to get by me after Dario blocked and I was not able to catch back up. Overall though, it was a great result for the team."
While Power still leads the championship, Castroneves moved up to third place with Sunday's victory and Briscoe remained fifth in the standings.
With his winning effort, Castroneves broke the IndyCar Series record for most laps led in a career, surpassing former Team Penske standout and current Penske Racing NASCAR driver Sam Hornish Jr. Castroneves has led 3,487 laps in his IZOD IndyCar Series career.
"I was very focused today," said Castroneves. "There was one point on a restart that I had a moment in Turn 4, but that was the only issue that I had the whole race. Once my boys put me back in the lead and into the clean air, I was very comfortable."
Team Penske has now won nine of the 16 IndyCar Series races this season. The team has produced 92 victories on oval tracks and 153 wins overall, more than any team in open-wheel racing.
Castroneves said that Team Penske remains focused on Power's run for the championship, which will be decided at Homestead. "He's 12 points ahead, and it's better to be 12 points ahead than 12 points behind," said Castroneves. "He had a great performance today. Anything we can do to help him bring the championship to Team Penske, we're going to do it."
The IZOD IndyCar Series season concludes on Saturday evening, October 2, with the Café do Brasil Indy 300 at Homestead-Miami Speedway. Live coverage will begin on Versus at 6 p.m. ET.