Ryan Briscoe grabbed the IndyCar series points lead by stringing together quietly consistent finishes. Then he took control by putting on a remarkable wheel-to-wheel show under the lights at Chicagoland Speedway on Saturday night.

Briscoe made an aggressive move for the lead going into the final lap of the race, pulling alongside fellow title contender Scott Dixon as the white flag flew. After going side-by-side with their wheels inches apart, Briscoe nosed ahead at the finish line to win by 0.0077 seconds.

Told that his margin of victory _ the fourth-closest finish in series history _ translated to about 28 1/2 inches on the track, Briscoe didn't balk.

"Nice," Briscoe said. "That's enough."

Dixon finished second by a nose, followed by Mario Moraes and the third remaining championship contender, Dario Franchitti. Three of the series' four closest finishes have come at Chicagoland.

The series title fight remains tight going into the final two races of the season, but Briscoe's third victory of the season represents a significant boost to his title hopes.

Briscoe came into Saturday's race with a slim five-point lead over Franchitti, but leaves Chicagoland leading Franchitti by 25 points and Dixon by 33 points going into the final two races.

Briscoe said extending his lead slightly won't change his strategy.

"No different, really," Briscoe said. "We've seen how quickly that can turn around. Just got to stay focused and try to beat these guys still."

Afterward, Dixon was unhappy that his Chip Ganassi Racing car seemingly wasn't able to keep pace with Briscoe's Penske Racing car.

"Pretty simple _ we didn't have enough speed," Dixon said. "I could tell if it was going to come down to a head-to-head race at the end or the finish with Ryan or even Helio (Castroneves), we weren't going to have enough."

But it was a rough day for Castroneves, Briscoe's Penske teammate, who appeared to break a suspension part and hit the wall with 16 laps to go.

Castroneves, who came into Saturday night's race fourth in the points, was eliminated from title contention after his crash. According to series officials, X-rays on Castroneves' right ankle were negative and he was released from the infield medical center.

Franchitti said Castroneves' elimination helps the Penske team, because Castroneves can race in support of Briscoe's bid for the title while the Ganassi teammates presumably continue to race Briscoe, and each other, for the title.

"Ryan's got the luxury of Helio being out of it, so he can help him a little bit," Franchitti said. "But us, both cars are still in the fight right now. I don't know, if we end up backing one horse, Chip (Ganassi) will make that decision. But as of right now we're both still going for it."

Graham Rahal rounded out the top five. Danica Patrick finished 12th.

The race was fast and caution-free until nearly the halfway point, when Andretti Green Racing driver Hideki Mutoh lost control of his car and hit the wall hard on lap 92. Mutoh was able to climb out of the car on his own.

All the leaders pitted on lap 96, putting the leaders close to making it to the end of the race with only one more stop.

Briscoe had a slightly slower stop than the rest of the leaders _ apparently misjudging his marks while coming to a stop _ and came out in eighth place for the restart. Briscoe struggled in traffic during the middle portion of the race and fell out of the top 10 at one point.

"I wasn't too worried at the time," Briscoe said. "But once we got going, I got a little bit more worried because there were a lot of fast cars out there tonight."

But he eventually climbed back into the lead when Franchitti pitted under green with 42 laps remaining. Franchitti's stop was slowed when a mechanic's air wrench briefly got stuck under his car.

Briscoe and Dixon pitted soon after, and Dixon took the lead back after all the leaders cycled through the pits.

After Castroneves' crash, Dixon led the field to a restart with nine laps to go.

But Briscoe pulled alongside Dixon as they took the white flag signaling one lap to go, and raced him side-by-side for the remainder of the final lap before inching past him as they came to the finish line.

"We did our best job, and we still came up short," Dixon said.