INDIANAPOLIS (AP) — An unfamiliar driver ushered in a new era of the Indianapolis 500 by outlasting his faster rivals — and his fuel tank.

American Alexander Rossi was the stunning winner of the historic 100th running of “The Greatest Spectacle In Racing” on Sunday in a victory that allowed the long-suffering Andretti family to celebrate in the biggest race of their famed careers.

Rossi was a 66-to-1 long shot and certainly not the driver anyone would have picked to win. But the 24-year-old Californian used fuel strategy to outsmart a handful of drivers who had the most dominant cars in the race.

Rossi 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 team co-owner Bryan Herta to conserve fuel, and he ultimately ran out of gas after taking the checkered flag.

His victory celebration came only after his Honda was towed to the party. He sat in the car for some time before climbing out to take that sweet sip of milk.

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

“I really was focused on taking it one lap at a time,” Rossi said. “The emotional roller-coaster of this race is ridiculous. There were moments I was really stoked, really heartbroken, really stoked. I was like, ‘Wow, I’ll need to see a psychiatrist after this.”’

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. He 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,” Munoz said. “I was really disappointed to get second. Half a lap short. What can I say? The only thing I’m clear about is that I will win this race one day.”

Munoz has contended at Indy before and he’s proven to be fast at the speedway.

Rossi? Well, not many know much about him at all.

He’s an IndyCar rookie who has chased a ride in Formula One since he was 10. He left for Europe when he was 16 and never pursued a career in American open-wheel racing. But stuck without a ride this year, he made the decision to return to the United States to race and became the ninth rookie to win the 500 and the first since Helio Castroneves in 2001.

Rossi understood full well that it was strategy that got him this win, and he knows what an Indy 500 victory means.

“I have no doubt it’s going to change my life,” he said.

Although he’s a relief driver for Manor Racing in F1, Rossi has no scheduled F1 races and IndyCar right now is his top commitment. He was lured back to America this year to drive for Bryan Herta in a partnership with Andretti Autosport. Herta was the winning car owner in 2011 with Dan Wheldon, the actual 100th anniversary of the first race in 1911, and now can claim a win in the 100th actual race.

“I can’t compare (the wins) other than to say I am so happy,” Herta said. “ I can’t overstate how hard it was for Alex to do what I was asking of him on the radio.”

This Herta effort relied heavily on its alliance with Andretti, and the family 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 clearly 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.

“Ryan and Townsend looked really good up front, we thought they would be the team to beat,” team owner Michael Andretti said. “Unfortunately, they had their problem in the pit, which I could not believe, and I thought that may have been our shot at winning.”

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.

“I knew Alex was going to try (the fuel strategy), and we said ‘Alright, if he’s going to try it, we’re going to try something else (with Munoz),” Andretti said. “To come home 1-2 is just incredible. It was amazing. I don’t know what to say, it’s a great day, to be a part of history, to win the 100th running, and to win it with a 1-2 finish is just incredible.”

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 this race last year after a near-fatal accident in a practice session, faded to seventh despite being one of the best cars in the field.

“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.”

In front of the first sellout in Indy 500 history, Rossi stunned the more than 350,000 fans in attendance. He was in Monaco this time last year for F1’s signature race, unsure of what his future held.

“I had no idea I’d be in IndyCar, I had no idea I’d be in the Indy 500,” said Rossi, who becomes the 70th winner in race history.

He will now also become the 103rd face on the famed Borg-Warner Trophy.