William Byron wins the NASCAR Xfinity Series championship

Dale Earnhardt Jr. got the best retirement gift he could have asked for when William Byron won the Xfinity Series championship for JR Motorsports on Saturday, one day before Earnhardt’s final race as a full-time driver.

NASCAR’s most popular driver is a part owner of the race team with sister Kelley and boss Rick Hendrick, and JR Motorsports went in to the finale at Homestead-Miami Speedway with a 75 percent chance of winning the title. JRM drivers Justin Allgaier, Elliott Sadler and Byron were up against Daniel Hemric of Richard Childress Racing for the championship.

Hemric appeared up for the challenge at the start and he led the title contenders until he headed to pit road with a dead battery early in the second stage. The team frantically changed the battery, but his car still had no power after the swap. When Hemric finally got back on the track, he was down 12 laps from the leaders.

That sealed the title for JRM, and the organization only had to watch to see which of its three drivers would take the crown.

Earnhardt and Hendrick watched intently from the top of Byron’s pit box. Kelley Earnhardt Miller watched from another. Earnhardt moved to Sadler’s pit stall.

Calling the race for Allgaier? Seven-time championship-winning crew chief Chad Knaus, who was filling in for Allgaier’s suspended crew chief. Earnhardt likened the call to the bullpen to having Joe Gibbs coach a kid in Pop Warner football.

Although a second title for JRM was in the bag, it wasn’t without anxious moments.

Sadler and Byron had a spirited battle for the championship as they raced each other for position for several laps. The two had contact at least once, and it took Sadler until 36 laps remaining to get past Byron. But Byron came charging back, and the two again raced aggressively for position with nine laps remaining.

Sadler was held up by another driver and Byron passed him for good with nine remaining. As the laps wound down, Sadler grew more aggressive and hit the wall.

Cole Custer, meanwhile, easily won his first career Xfinity Series race. It came a week after he was eliminated from the playoffs. He had leads of up to 15 seconds as he was out front for all but 15 of the 200 laps.

The Custer race victory was a win for Ford, but the championship went to Chevrolet. That was a given before the race because all four finalists were in Chevys.

It’s the second championship for JRM, which won its first title with Chase Elliott in 2014. Elliott graduated to the Cup Series, and Byron is taking over the No. 24 at Hendrick Motorsports next season.