INDIANAPOLIS (AP) — Alexander Rossi spent the biggest weekend in auto racing last year in Monaco, looking for a television that was broadcasting the Indianapolis 500. Back then, American was still hoping he could land a full-time ride in Formula One.

He eventually ran out of time.

On Sunday, in the biggest race of his life and as a rookie driver to boot, Rossi almost ran out of gas.

Almost.

Instead, the 24-year-old Rossi outlasted his faster rivals and his fuel tank for a stunning victory in the historic 100th running of the Indianapolis 500, landing him atop the biggest podium in motorsports after his car ran out of gas on the victory lap. This was a win no one — not even Rossi — could have predicted when he decided to return the United States and give IndyCar a chance.

"He had no idea. He honestly had no idea," said team co-owner Michael Andretti. "He was 100 percent Europe, the way he was training and everything. He never even saw an oval except for Phoenix before this."

Indeed, Rossi decided at age 10 he wanted to be an F1 driver. He left California for Europe six years later and spent a frustrating time bouncing around as a test driver.

But his options had grown cold, and when Bryan Herta needed a miracle to remain in IndyCar, he signed Rossi and merged his team with Andretti Autosport. That partnership gave Rossi four teammates to work with at Indianapolis Motor Speedway, and the 24-year-old California native needed help from all of them to make Sunday's win possible at the centennial edition of "The Greatest Spectacle In Racing."

"We've had our struggles. It's been a new experience for me," said Rossi. "We've worked very hard every day to try to improve and get things better. It's just a huge testament to the great people I have around me."

Rossi's win allowed the long-suffering Andretti family to celebrate in the biggest race of their storied careers and it left the top drivers in the field fuming over Rossi's good fortune.

Rossi, a 66-to-1 long shot, stretched his final tank of gas 90 miles to cycle into the lead as others had to duck into the pits for a splash of fuel in the waning laps. He was sputtering on the final lap, working his clutch and getting screamed at by Herta to conserve fuel. He made it — barely.

His victory celebration came only after his Honda was towed in so he could climb out to take that sweet sip of milk.

"I have no idea how we pulled that off," he declared.

"The only actual site of an oval that I'd ever been to was Phoenix in February, I'm definitely a rookie on ovals," he said. "Obviously street courses I have an understanding about. But IndyCar is a whole different can of worms than anything I've been a part of. It's incredibly competitive and incredibly close. You have to be perfect all three days, everyone around you, drivers and teams."

Rossi didn't have the speed of Carlos Munoz, who was charging hard over the final 50 miles. But Munoz also had to stop for gas and didn't have a chance to race his teammate for the victory, even though Rossi was running on fumes and completed the final lap at a snail's pace of 179.784 mph.

The Colombian settled for second in a 1-2 finish for Andretti Autosport and for Honda. Munoz seemed devastated after his second runner-up finish in four years.

"I was really disappointed when it comes with fuel and you lose the race because of that," he said. "Half a lap short. What can I say?"

Rossi became just the ninth rookie to win the Indy 500 and the first since Helio Castroneves in 2001.

Although he's a relief driver for Manor Racing in F1, Rossi has no scheduled F1 races and he described his role as a reserve driver: "I sit around and pretend to look important. There is no driving involved. I drive to the track in a rental car."

He was important Sunday, particularly for an organization that was hoping Marco Andretti would give them their first Indy 500 title since patriarch Mario Andretti won in 1969.

Instead, Marco Andretti never contended on a day at least three of his teammates were among the best in the field. Ryan Hunter-Reay and Townsend Bell combined to lead 64 of the first 119 laps, but the Americans were knocked from contention when Bell clipped Castroneves as he left pit road. The contact caused Bell to crash into Hunter-Reay.

Herta decided to gamble with Rossi on fuel strategy, and it's the only thing that made him a late contender.

As the laps wound down, American Josef Newgarden and Munoz repeatedly swapped the lead. Both had to stop for gas, Rossi moved into the lead and it was all his from there. Michael Andretti earlier this month was voted by the 27 living winners as the best driver never to win the race, but he has now won the 500 four times as a car owner.

Newgarden finished third and was followed by Tony Kanaan, Charlie Kimball and JR Hildebrand as Chevrolet drivers took spots three through six.

Newgarden, along with Hunter-Reay, Bell, Kanaan and James Hinchcliffe, had the strongest cars most of the race. Hinchcliffe, the pole winner who missed the race last year after a near-fatal accident in a practice session, faded to seventh.

"If I was in Alex's position, I'd be the happiest person in the world right now, I wouldn't care how we won the damn race," Newgarden said. "Everyone was on different strategies, and they played that strategy. Those guys, to put it politely, weren't as strong as us. They didn't have as strong a chance to win, so they had to mix it up. It worked out at the end for them."

And now Rossi knows IndyCar is his top commitment.

"I have no doubt it's going to change my life," he said.