LAS VEGAS -- AJ Allmendinger won a two-lap sprint to the finish Saturday night for his first victory of the season and an automatic berth in the NASCAR Xfinity Series championship finale.
Allmendinger won at Las Vegas Motor Speedway by leading a race-high 102 laps in the No. 16 Chevrolet for Kaulig Racing then holding off Ryan Sieg in a final sprint.
A caution with six laps remaining gave Sieg a late chance to snatch the win from Allmendinger, but he got a huge shove from Justin Allgaier on the restart and pulled away to beat Sieg by 0.156 seconds.
Allmendinger started the race -- the opener of the semifinal round of the Xfinity playoffs -- seventh out of eight and below the cutline.
The veteran, who will make a full-time return to the Cup Series next year, was in need of either a victory or three good finishes to make the championship finale. Allmendinger raced for the Xfinity title in 2021.
"It's good to get to Phoenix after the year we've had," Allmendinger said. "Let's go win a championship! Let's go!"
He dedicated the win to team owner Matt Kaulig, saying he had promised his boss he would win the race as a birthday gift.
Sieg, who is not in the playoffs, finished second in a Ford and was followed by playoff-driver Allgaier in a Chevrolet for JR Motorsports.
Chandler Smith, another playoff driver, finished fourth in a Toyota for Joe Gibbs Racing.
The next two spots went to non-playoff drivers Riley Herbst and Parker Kligerman, who were both eliminated last week at Charlotte.
Cole Custer, who is still in title contention, finished seventh. The remaining playoff drivers were Jesse Love (ninth), Austin Hill (12th), Sam Mayer (13th) and Sammy Smith (26th).