Gilliland showed early his No. 38 Ford had speed but he was saddled with a pit-road penalty for a crew member over the wall too soon and had to restart the second stage from the rear of the field.
With nine of 41 laps remaining in the race, Gilliland had worked his way back to second and reclaimed the lead with five laps to go. He ended up easily holding off Kaz Grala by nearly eight seconds.
The win is Gilliland’s first of the season and just the second of his career. His first career victory came at Martinsville, Va., in the 2019 season. He also collected an additional $50,000 bonus as part of the Triple Truck Challenge program.
Gilliland became the first NASCAR winner at the 3.41-mile, 20-turn Circuit of the Americas. All three NASCAR national series are making their debut at the road course this weekend.
“I definitely did a lot of stuff wrong but that’s what I love about road course racing, there’s 20 turns here, 20 opportunities to pass, but also make mistakes,’’ Gilliland said.
“Last year, we didn’t quite have the season we knew we could and just to come out here and win early, we’ve been building momentum and for my team to get this win is just amazing.’’
Tyler Ankrum finished third, Grant Enfinger was fourth and Sheldon Creed rounded out the top-five.
Completing the top-10 were Sam Mayer, Carson Hocevar, Zane Smith, Austin Hill and Ben Rhodes.
Following the break between Stages 2 and 3, several lead-lap trucks pit while Creed stayed out and inherited the lead. He led the way when the race returned to green on Lap 29.
With 10 laps to go in the race, Ankrum closed to within a second of Creed as Grala moved into third.
Ankrum finally worked his way around Creed after the two made contact near Turn 19 as they were about to begin Lap 33.
Gilliland caught Creed and with nine laps to go and finally got around him near Turn 2 with eight laps to go to take second place.
With just over six laps remaining, Gilliland returned to the lead after a wild duel with Ankrum.
The biggest obstacle remaining was the quickly drying track as the entire field remained on wet-weather tires.
With four laps to go, Gilliland’s lead over Ankrum remained at almost 4 seconds while Grala remained third, 5.4 seconds behind the leader.
Grala quickly got around Ankrum to take over second and began working on running down Gilliland for the lead.
Rhodes grabbed the lead with two laps remaining as some leaders elected to pit and cruised to the Stage 2 win, 6.2-seconds ahead of Matt Crafton.
Derek Kraus was third, Creed fourth and Ankrum rounded out the top-five.
Following the break between Stages 1 and 2, several lead-lap trucks pit but Creed remained on the track and inherited the lead.
Both Gilliland and Hailie Deegan were penalized during their respective stops for having crew members over the wall too soon and had to restart from the rear of the field.
When the race returned to green on Lap 15, Creed was followed by Enfinger and Zane Smith.
On Lap 18, Mayer got around Enfinger to take over the runner-up spot behind Creed.
Zane Smith spun in Turn 1 on Lap 20 and suffered a left-rear flat, forcing him to limp back around the entire track to pit road.
With five laps remaining in the second stage, Creed held a 5.2-second lead over Grala while Ankrum ran third.
Once again, several lead-lap trucks elected to pit prior to the conclusion of the stage, including Deegan, Chandler Smith and Mayer. Creed and Ankrum both pit with three laps remaining.
While making his stop on Lap 24, Nemechek was penalized for an uncontrolled tire. He will have to restart from the rear of the field following the stage break.
Rhodes inherited the lead with two laps remaining.
Gilliland methodically ran down Grala and passed him on the final lap to claim the Stage 1 victory.
Ankrum finished third, Crafton was fourth and Rhodes rounded out the top-five.
Ankrum started on the pole but Grala wasted little time taking the lead away on the first lap as Crafton moved into second.
On Lap 5, both Tate Fogleman and Deegan spun in Turn 20 but both were able to continue.
On Lap 6, Roger Reuse blew through Turn 5 and was assessed a pass-thru penalty on pit road by NASCAR.
With five laps remaining in the first stage, Grala opened up a 1.6-second lead over Creed while Ankrum ran third.
A handful of trucks elected to pit with three laps remaining, including Zane Smith, Enfinger and Parker Chase. With two to go, Creed – who was running second – also elected to pit.
Five trucks had to start the race from the rear of the field – Ryan Truex and Tanner Gray for an engine change, Lawless Alan for a transmission change and Chase Purdy and Austin Wayne Self for unapproved adjustments.