William Byron had the field covered at Watkins Glen International, delivering such a dominant performance that no other NASCAR driver even got to his bumper in the final third of the race.

It was unusual for the Cup Series and even more rare for Byron at a road course. The 25-year-old driver won on a serpentine track for the first time in six Cup seasons, this one being his series-leading fifth victory of the season and making him a favorite to win it all.

“We’ve worked years and years for this,” Byron said, crediting veteran open-wheel racer Max Papis with helping him. “It’s a great win. I don’t know what it means and all that. I don’t read into that. But I think it shows that when we’re at our best, we can perform like this.”

Driving the No. 24 Chevrolet for powerhouse Hendrick Motorsports, Byron overtook Michael McDowell in the first quarter of the 90-lap event and pretty much remained in control the rest of the way. He led 66 laps in all, including the final 33.

Pole sitter Denny Hamlin was second, nearly 3 seconds back, in the penultimate race of NASCAR’s regular season. Christopher Bell was third, followed by AJ Allmendinger and Ty Gibbs.

Martin Truex Jr. finished sixth but failed to lock up the regular-season title for Joe Gibbs Racing. He and Hamlin will vie for the regular-season crown next weekend at Daytona International Speedway.

“It’s doable,” said Hamlin, who trails Truex by 39 points. “You’ve got to have things go your way, but yeah. If we can talk NASCAR into those 25 points they took away earlier in the season, we’d really make it interesting.”