INDIANAPOLIS - J.R. Hildebrand was one turn away from winning the Indianapolis 500 and within sight of the checkered flag when the 23-year-old rookie made the ultimate mistake.

Leading by almost four seconds with a lap to go, Hildebrand skidded high into the wall on the final turn, and Dan Wheldon drove past to claim an improbable second Indy 500 win Sunday in his first race of the year.

"It's a helpless feeling," Hildebrand said.

Wheldon, the 2005 winner but without a full-time ride this season, appeared headed for his third straight runner-up finish when Hildebrand took the white flag needing only to make it through the last of 200 laps around the 21/2-mile speedway.

The first three turns went smoothly. Then Hildebrand came up on another rookie, Charlie Kimball, in the fourth turn.

Instead of backing off, Hildebrand moved to the outside to make the pass and lost control, slamming the wall to a collective gasp from the crowd of 250,000.

"I caught him in the wrong piece of track," Hildebrand said. "I got up in the marbles and that was it."

Hildebrand's crumpled machine slid across the finish line, still hugging the wall, in second place. While Wheldon celebrated, IndyCar officials reviewed the video to see if Wheldon passed the wrecked machine before the caution lights went on. He clearly did, and Hildebrand's team, Panther Racing, said it would not protest.

"I just felt a lot of relief. It's an incredible feeling," Wheldon said. "I never gave up."

He took the traditional swig of milk and headed off on a triumphant lap around the speedway - a lap that Hildebrand should have been taking.

Instead, the youngster stopped by the garage to get a look at his mangled car, which was hauled through Gasoline Alley instead of being wheeled into Victory Lane.

"I'm just frustrated. It's not because we came in here with the expectation of winning and we didn't," Hildebrand said. "I felt like I just made a mistake and it cost our boys. I guess that's why rookies don't win the Indianapolis 500 a whole lot and we'll be back next year, I guess."

The 100th anniversary of America's most famous race was dominated much of the day by Chip Ganassi's top two drivers, defending champ Dario Franchitti and 2008 winner Scott Dixon.

But after a series of late pit stops, things really got interesting. Second-generation racer Graham Rahal spent some time up front. Danica Patrick claimed the lead but had to stop for fuel with nine laps to go. Belgium driver Bertrand Baguette had already gotten past Patrick, but he didn't have enough fuel, either.

When Baguette went to the pits with three laps to go, the lead belonged to Hildebrand. All he had to do was make it to the end.

He came up one turn short.

"My disappointment is for the team," Hildebrand, who lost by 2.1 seconds, said. "We should've won the race."

"Dan Wheldon, he's a great winner," Patrick said. "And what a great story. He hasn't run this year. . . . That's really cool."

Still, it was a bitter disappointment for Patrick, who ended up 10th.

"It's more and more depressing when I don't win the race," said Indy's leading lady.

For Hildebrand, the cheers turned to groans on the final turn.

"It's just a bummer," he said.