Hornaday, the four-time series champion, started on the pole and put on a dominating performance by leading 107 of 146 laps for his fourth win of the season and the 51st of his career. He won two weeks ago at Kentucky. Hornaday also benefited from Austin Dillon and James Buescher's wrecks early in the race to move him from 42 points to 21 out of the lead.
It's the first time Hornaday has won at Las Vegas in 11 races here.
Dillon, the defending race winner, brought out the first of 10 cautions in the 219-mile (350-kilometer) race when he made contact with the wall on the second lap. He wound up finishing 15 laps down in 17th. Dillon managed to hold on to the points lead. His advantage is five points over Johnny Sauter, who finished fourth.
Buescher trailed Dillon by three points heading into this race, but he ran into the back of Blake Feese after Feese spun around on lap 47. Buescher fell 40 laps behind and ended up finishing 21st. He is currently seven points behind Dillon.
Seven cautions occurred within the first 70 laps. This was the first time the series competed on this 1.5-mile track during the day since 2002. Teams were not used to racing conditions here during the afternoon hours.
A four-car wreck on lap 30 forced NASCAR to halt the race for 10 minutes. Ricky Carmichael got hit from behind and then spun around, collecting Brian Ickler and Miguel Paludo.
The final caution set up an eight-lap shootout to the finish. Hornaday pulled away from second-place runner Matt Crafton after the restart and then beat him to the finish line by 0.6 seconds.
Crafton's second-place run came in his 268th straight truck start, as he surpassed Dennis Setzer for second on the series' all-time consecutive starts list. Terry Cook holds the record with 296.
Timothy Peters' third-place finish put him back in the title fight as well. Peters is 25 points behind the leader.
Todd Bodine, the 2010 series champion, finished fifth, followed by Nelson Piquet Jr., David Mayhew and Cole Whitt.
Brendan Gaughan and Parker Kligerman completed the top-10.
Just four races remain in the season -- Talladega (next Saturday), Martinsville (October 29), Texas (November 4) and Homestead (Nov. 18).