AP photo by Steve Marcus / Joe Gibbs Racing driver Denny Hamlin celebrates after winning Sunday night's race at Las Vegas Motor Speedway.

LAS VEGAS — Turns out 21 was Denny Hamlin's lucky number in Vegas.

After finally getting the first Las Vegas Motor Speedway victory of his NASCAR Cup Series career on his 21st try, Hamlin is on an undeniable hot streak he just might ride all the way to his long-sought first season championship on the top circuit.

Hamlin finally broke through by holding off reigning Cup Series champion Chase Elliott on Sunday night to kick off the second round of the playoffs with his second win in September. Three weeks after Hamlin got his first victory of the season in the playoff opener at South Carolina's Darlington Raceway, he led 137 laps in the No. 1 Joe Gibbs Racing Toyota, including the final 39.

After a season of frustrating results and a 17-year career filled with closes calls in the title chase, Hamlin has emerged as a serious contender to win it all once again. He is just 14 points behind Kyle Larson in the points standings, and he'll have no pressure heading into the high-stakes upcoming races at Alabama's Talladega Superspeedway and on the Roval course at North Carolina's Charlotte Motor Speedway with his ticket already punched for the third round by his Vegas victory.

"It feels so good to win in Vegas," Hamlin said. "Last couple of times I've been close but just didn't have the right breaks. Great to hold those guys off."

Hamlin, 41, had struggled on this 1.5-mile track for most of his career, with just two top-five finishes in his first 18 starts. He has put together three consecutive top-four finishes since then at Las Vegas, capped by this celebration under the lights and fireworks.

"There was a point where I never thought I'd even sniff a victory here," Hamlin said. "The team has found a setup that has worked with my driving style. The team goes to work to give me what I need to go fast."

Elliott closed in on Hamlin in the final five laps as the leader's performance appeared to decline, cutting the gap to a half-second with two laps to go. That was it, though, as Elliott wound up second in the Hendrick Motorsports No. 9 Chevrolet.

"We were really close," Elliott said. "Just not quite close enough. Denny did a good job controlling the gap to me. I feel like we've been performing at a really nice level the last four or five weeks. Just haven't had the results to show for it."

Kyle Busch finished third on his hometown track, followed by JGR teammate Martin Truex Jr. and Team Penske's Ryan Blaney as the 12 remaining playoff drivers began the second round and the final seven races of the season.

Hamlin has made the playoffs 15 times, but he came closest to a championship in 2010. He won eight races that year and took a points lead into the season finale at Homestead-Miami Speedway, only to end up second behind Jimmie Johnson with a 14th-place finish in the race.

"I just can't think of a better place to win," said Chris Gabehart, Hamlin's crew chief. "Certainly our team has been really capable all year long. Every metric other than the win column has been astounding for our team. It's really been our best year together thus far. You stay up front as much as we have, the wins are going to finally come. They're coming at the right time."

Stewart-Haas Racing's Kevin Harvick, who scrapped with Elliott over tactics during the previous race at Tennessee's Bristol Motor Speedway, finished ninth.

Larson finished 10th on the track where the Hendrick driver won in March for the first of his series-leading six points victories this year. He won the first stage Sunday, but Hamlin took the second when Larson needed gas and pitted with eight laps to go. Larson got stuck in the midfield in the final stage while struggling with his tires.

Harvick wasn't really in position for any payback on Elliott after the younger driver deliberately slowed Harvick at Bristol the previous weekend, ruining his chances of catching Larson. Harvick and Elliott had a vocal public disagreement after that race.

Harvick was still sore about it in Vegas, calling it "probably the maddest I've ever been."

"It was like speaking to a 9-year-old," Harvick, 45, said of his argument with the 25-year-old Elliott. "It's identical. It's 100% the exact same scenario. They get hung up on one thing, and you can't speak to them about the broader picture about how the whole thing works."

Kyle Busch was strong in his 600th career Cup Series start, and older brother Kurt finished eighth in his 750th career start. The Las Vegas natives have been racing this track on the far north end of Las Vegas Boulevard since it reopened at its current configuration in 1996.

The only driver in NASCAR history who made 600 starts at a younger age than Kyle Busch is Richard Petty.