In exactly the kind of thrilling final lap, final-turn high-action finish NASCAR has so often provided on road courses, Ross Chastain persevered in the EchoPark Automotive Grand Prix to win his first career NASCAR Cup Series race at the Circuit of The Americas in Austin, Texas - the sixth different winner this season.

Chastain really had to earn this one - coming out on the right end of a frantic, four lead-change, two-lap final overtime. And he did - moving veteran A.J. Allmendinger and Alex Bowman in the final series of turns on the 3.41-mile, 20-turn circuit to take not only his first victory in NASCAR's premier series but also give his Trackhouse Racing's Justin Marks his first win as a new owner in stock car's big leagues.

After grabbing the position in the final corner, Chastain raced off to a 1.331-second victory over Hendrick Motorsports driver Bowman, who unlike Allmendinger was able to recover from the last lap contact and continue to the checkered flag. Joe Gibbs Racing's Christopher Bell, Hendrick Motorsports Chase Elliott and Richard Childress Racing's Tyler Reddick rounding out the top five.

Chastain's family owns a watermelon farm in tiny, rural Alva, Florida and as he has famously done with past victories in both the NASCAR Camping World Truck Series and Xfinity Series, Chastain stood on top of his winning car, the No.1 Trackhouse Racing Chevrolet, and dropped a watermelon to the track, crushing it on the ground as his team and fans exploded in cheers.

"It's insane to go up against some of the best, and I know he's [Allmendinger] going to be upset with me, but we race hard, both of us," said Chastain, who has been runner-up in the last two NASCAR Cup Series races coming to Austin.

"But when it comes to this Cup win, I can't let that go down without a fight."

Allmendinger, who actually was a NASCAR Xfinity Series teammate with Chastain two years ago, was understandably crushed as well after the race. He finished 33rd.

"We just needed two more corners," said a disappointed Allmendinger, who also went door-to-door in a tight on-track battle with Chastain in winning Saturday's NASCAR Xfinity Series race at COTA.

"Everybody's got to be comfortable with the move they make and look in the mirror," Allmendinger told FOX Sports. "Everybody's different on what they view, and you can't judge a person for that.

"So, at the end of the day, I'm just proud of Kaulig Racing for bringing such a fast Action Industry Chevrolet. We started at the back, drove to the front and if we had had a long run [at the end] it would have been game over. Nobody would have touched me.

"You know the moves are going to be made at times. Whether I'm okay with it, doesn't really matter.

"I wanted to sweep the weekend, and we came two corners away," he added.

Chastain led a race high 31 of the 69 laps - one of nine leaders in the series' first road course test with the Next Gen cars debuting this season. The race produced a series road course record of 30 green flag passes for the lead.

And the 29-year-old Floridian becomes the 12th consecutive NASCAR Cup Series race winner under the age of 30 and the third first-time winner this season.

It was as equally a thrilling maiden win for the former NASCAR and sportscar driver Marks, who was interviewed during the FOX telecast just before the final restart, revealing with a smile that "It's a little easier to be a driver of one these things than to watch."

"It seemed like a real tall order when I dreamt this thing up," Marks said. "But every man and woman that's trusted the vision and committed to Trackhouse and worked so hard owns a piece of this victory.

"I'm so happy for everybody. Everybody believed in this, and I can't wait for next week."

And, he reported with a grin, he spoke with the team's co-owner, music superstar Pitbull who promised he also was smashing a watermelon over his head and drinking champagne.

The race pole-winner Ryan Blaney finished sixth, followed by Martin Truex Jr, Austin Cindric, Erik Jones, and Austin Dillon rounding out the top 10.