HOMESTEAD, Fla. -- When 10 months came down to 10 laps, youth topped experience.
Nineteen-year-old wunderkind William Byron captured the 2017 NASCAR Xfinity Series championship Saturday, finishing third in the EcoBoost 300 at Homestead-Miami Speedway. He edged Elliott Sadler, 42, his JR Motorsports teammate who served as his shadow much of the race -- and led Byron heading into the final 10 laps -- but ended up eighth.
For Byron, who was also named Xfinity Series Rookie of the Year, it capped his first and only season on the circuit. He'll make the jump up to the Monster Energy NASCAR Cup Series, driving for Hendrick Motorsports, in 2018.
For Sadler, it was the second year in a row he finished second, after he was runner-up behind Daniel Suarez in 2016.
"This is an incredible feeling," Byron said. "We learned a lot this year. (Crew chief Dave Elenz) and I got so much better together. We really were at our best the last few races. ... It's a total team effort. It's really cool."
Byron and Sadler, half of the Championship 4 vying for the Xfinity Series title Saturday, were neck and neck for many of their 200 laps. The driver who finished first among them, Daniel Hemric and Justin Allgaier (in the entire field of 40) would earn the crown.
Hemric encountered battery trouble around lap 61, costing him about 10 laps and effectively ending the competitive portion of his day. Allgaier hung around for much of the race, but was consistently a couple of spots and several seconds behind Byron and Sadler.
That made it a two-car competition, Byron's No. 9 Chevrolet and Sadler's No. 1 Chevrolet.
Byron passed Sadler for good on lap 191, making a push on the lower half of the track. Moments later, Sadler tried to rebound, but got pinched by Ryan Preece of Joe Gibbs Racing and ended up losing significant ground.
Sadler confronted Preece in pit row immediately after the race. He said he was disappointed to get squeezed out by someone who, by that point, wasn't racing for anything. Preece said he was racing for the owners championship, though that appeared to be decided by those waning laps.
"When I dove down into 1, I thought he was going to give it to me and I was going to slide in front of him," Sadler said, lamenting that this was the closest he has come to a championship in a pro career that is older than Byron. "And he just gassed it and pinched me down. That was it. That's pretty hard to swallow.
Said Preece: "I can't not listen to my owner, the guy who's paying you in the end, so it's just a tough deal. It's crappy in the end -- but I hate controversy. ... To be honest with you, if there's a person you don't want to cost a championship to it's Elliott Sadler."
Sadler was despondent.
"I've been racing a long time," Sadler said. "I would say tonight is the most devastated and down-and-out I've felt in my career.
Cole Custer, 19, also capped his rookie year with a title. He finished first in the EcoBoost 300 for the first win of his career.
"We just had an extremely good car, the whole weekend really," Custer said. "We came down here and tested it a couple months ago, and the second we hit the track we knew we were going to be good the whole time."
Driving for Stewart-Haas Racing, Custer, who won all three stages, had a perfect driver rating of 150.0 Saturday, the only driver to accomplish that in the Xfinity Series in 2017.
Team Penske won the Xfinity Series owners championship Saturday, its fourth in the past five years.
Penske's No. 22 car had four wins, 23 top-five finishes and 28 top-10 finishes this season. The last of those came Saturday, when Sam Hornish Jr. came in second.
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