As Colton Herta set up his winning pass Saturday, all he could see were red flashing lights. He still charged forward.

Colton Herta Indy Grand Prix

Herta won the IndyCar GMR Grand Prix in wet conditions. (AP)

The 22-year-old California driver quickly darted to the inside of Pato O'Ward on a late restart, took the lead for good with nine laps to go and beat Simon Pagenaud to the finish line by 3.0983 seconds to win a wild, wacky, wet IndyCar Grand Prix.

"Pure talent," Herta joked when asked how he persevered for his first win of the season despite the incredibly challenging weather conditions. "The most interesting thing is you never have a car that handles great in the wet and great in the dry, but it happened today."

Getting to victory lane certainly wasn't easy for Herta, who earned his first Indy win in his 10th series start at the track. He also became the first Honda driver to reach victory lane this season.

But on Saturday, he made all the right calls.

After qualifying 14th on the 27-car grid, he made the gutsy choice to switch from rain tires to dry tires just three laps into the race. While he initially struggled to keep the cold tires on the track and nearly spun out on Lap 4 when he got sideways in the 10th turn on the 14-turn, 2.439-mile road course, Herta never flinched.

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Somehow he hung on, quickly taking the lead and advantage of a move that allowed him to go from 15th to first. He stayed near the front of the pack the rest of the race, leading 50 of 75 laps in a two-hour race that had just 53 minutes, 22 seconds of green flag time.

Indy Grand Prix

Herta is sixth in the IndyCar season standings.  (AP)

It came on a day race strategists and drivers were constantly changing plans because of rain or the threat of rain. And even when it appeared Herta made the wrong choice — like running on dry tires after Alexander Rossi and made an early switch back to rain tires — things worked out.

"What I said is with the track conditions right now it’s probably wets, but it you think it’s going to be dry we’ll go with slicks," Herta said referring to the first of two late pit stops. "Immediately when I got out there, I knew it was going to be tough so we came back in. Luckily, everybody followed our lead and did the wrong thing so we didn’t lose too many spots."

Pagenaud and pole-winner Will Power struggled to navigate the spray coming off the other cars. Neither could see well enough for long enough in the first IndyCar rain race with the aeroscreens to catch Herta.

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Still, the the two three-time race winners and former teammates felt as if they too had accomplished something. Pagenaud, the French driver, gave Meyer Shank Racing its best finish of the season.

"That was nuts. The racing was phenomenal and the strategy was the name of the game today," he said. "Sometimes second feels like a win. I would have liked to win today, but we’ll probably celebrate tonight like it was a win."

Colton Herta

Colton Herta has seven career IndyCar wins (AP)

Power took the points lead away from defending series champ Alex Palou and posted Team Penske's best finish.

"At the end, you couldn't see. I can’t imagine being back in 10th or something," the Australian said. "Pretty crazy day, one to keep you on your toes and when to pick the right tire and don’t overdo it. Just survival."

Race organizers knew weather would be a factor.

They moved the start time up about 30 minutes with the hope of a wet track. Instead the start was delayed — first because of nearby lightning in the area and then because of a steady light rain.

The cooler, damper track changed everything. There were spins and crashes, even cars struggling to stay in line under caution. And nobody, not even the series' top names, were immune.

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Team Penske scrambled to get two-time series champ Josef Newgarden back on the course after his car was damaged in a Lap 17 crash. Power lost three spots on the first lap and never completely recovered and Scott McLaughlin, Penske's third driver, lost the lead when he spun under caution.

Six-time series champ Scott Dixon, the New Zealander who drives for Chip Ganassi Racing, ran out of fuel on pit lane. Dixon's teammate, Palou of Spain, fell out of contention when he, like Rossi, made the move back to rain tires too early.

O'Ward and Arrow McLaren SP teammate Felix Rosenqvist got tangled up in the first turn of Lap 42.

"I knew we could do it," Herta said. "Did I think we were going to win today in a normal dry race? No probably not. But we kind of adapted pretty well. It was a lot of fun."

GOOD BET?

Indianapolis Motor Speedway officials opened the first on-site betting lounge in track history Saturday.

The Caesars Sportsbook Lounge at Pagoda Plaza will remain throughout Indianapolis 500 practices, two days of qualifying and the May 29 race. Caesars Sportsbook also will sponsor the speedway's remaining races this year.

UP NEXT

Teams and drivers aren't going anywhere. Next up is the series marquee race, the Indianapolis 500 on May 29. Everyone gets a two-day break while the track is converted from a road course to the more traditional oval. Practice starts Tuesday and two days of qualifying are set for next weekend.