FONTANA, California: Ryan Hunter-Reay became the first American to win the IndyCar championship since 2006 with a thrilling final drive Saturday in the season finale.

Australia's Will Power crashed out of the race early, and had to watch on television in street clothes as Hunter-Reay snatched the title away at Auto Club Speedway.

Power's accident should have given Hunter-Reay a wide-open road to his first championship. Instead, he had to hang on for 500 nerve-racking miles, withstand several hairy restarts and a controversial red-flag to snatch the title away from Power on Saturday night.

Needing to finish fifth to win the title after Power exited the race, Hunter-Reay did one better, finishing fourth to put the American flag back atop the IndyCar podium.

Hunter-Reay claimed the title by three points over Power to become the first American since Sam Hornish Jr. in 2006 to win the IndyCar championship.

"I just drove 500 miles like it was for my life," he said. "I can't believe we're IndyCar champions. I cannot believe this. My dream has come true."

Power, denied for a third consecutive year, was in street clothes watching the finish on television after crashing out early at Auto Club Speedway. He took a 17-point lead into the finale, but once out of the race, gave Hunter-Reay total control of his destiny.

Hunter-Reay struggled all week at California, even wrecking in Wednesday's open test session, and was off at the start of the race. But he picked his way through the field and was on the edge of where he needed to finish as the laps wound down.

Still, a flurry of late cautions made for some hair-raising restarts and a late red-flag that drew the ire or team owner Michael Andretti. Hunter-Reay managed to hang on in a race that was won by Ed Carpenter, another American.

"We were struggling all weekend. I didn't want to let anyone really know about it that much. We were really in the woods," Hunter-Reay said.

Power, who has finished second in the points three years in a row, visited Hunter-Reay after the finish.

"At the end of the day, Hunter-Reay is a deserving champion, a real fighter," Power said.

Hunter-Reay won a series-best four races this season, his third with Andretti Autosport. He used a string of three consecutive wins during the summer to climb into the championship, and with Power in position to clinch two weeks ago at Baltimore, he won again to stay in the hunt.

He was rewarded on the eve of the championship race with a new two-year contract from Andretti, the team he has credited for giving him the continuity and support he needed to put together the best season of his career.

"It was really an unbelievable weekend," said Andretti, who won his fourth championship as an owner but first since 2007.

Power, meanwhile, was left wondering how yet another title slipped away.

He's the most dominant driver on road and street courses, and knows that racing on ovals is the one glaring weakness in his program. And when he looks back at this season, he knows that a blocking penalty at Texas and crashes on the ovals at Indianapolis, Iowa, and now, California, cost him the title.

"I wish I could put my finger on one particular thing I don't do right," Power said. "If you look at it, three ovals I crashed out of is a massive hit on points. It's over a whole season that you win a championship and that was proven tonight."

Power crashed 55 laps into the race, spinning hard into the outside wall when his car slipped in a seam in the track. It's the third consecutive year Power has gone into the finale with the title on the line and had an incident snatch away his chances.

He brushed the wall at Homestead in 2011 and lost the title by five points to Dario Franchitti. Last year, his points lead was gobbled up when another car hit him on pit road in the penultimate race, and he was involved in the 15-car accident that killed Dan Wheldon in the finale.

Power broke his back in that accident in Las Vegas.

"Man, depressing," Power said after leaving the wreck. "I wish I could care less."