ST. LOUIS, Mo. — Victories on the rough-and-tumble fifth-mile oval inside the The Dome at America's Center never come easy, but Brandon Sheppard’s Saturday night run from the front row in the 40-lap Castrol Gateway Dirt Nationals was about as uneventful as possible for 11 of the race’s 12 minutes.

RESULTS: 2023 Castrol Gateway Dirt Nationals

But when Sheppard caught a flash of a rallying blue car as his No. B5 was hampered by lapped traffic in the closing laps, the 30-year-old New Berlin, Ill., driver knew things were getting too close for comfort with Ricky Thornton Jr. bearing down.

“Lappers were all over me and I seen a blue car underneath me getting into (turn) one here,” Sheppard said, “and I was like ‘Oh snap, I better get up on the wheel here for these last corners.’"

With what had been a 2.5 second lead cut to nearly nothing with a lap to go, Sheppard withstood Thornton’s last-ditch bid at the lead in turns one and two on the final lap, pulling back away to win by 1.942 seconds at the checkers.

“It feels good man. I've been trying a long time,” said Sheppard, who had three top-five finishes at Gateway in six previous starts. “Every year I come here, I either run top four or get a flat tire. So I guess this year was my year finally. Luck kinda fell my way a little bit. The redraw (for an outside front-row starting position) really helped. Out front, Ricky would have been really hard to pass, too.”

The second-starting Sheppard collected $30,000 while the third-starting Thornton, his SSI Motorsports entry in tatters in part because he hit the wall after bailing out of a last-lap slide job attempt, then got hung up with a lapped car on the backstretch, settled for second to conclude his 34-victory season. The 10th-starting Tanner English of Benton, Ky., gained two positions in the final five laps for third with Devin Moran of Dresden, Ohio, and Chris Simpson of Oxford, Iowa, rounding out the top five.

VIDEO: Brandon Sheppard discusses his first career Castrol Gateway Dirt Nationals win. 

Provisional starter Tyler Erb of New Waverly, Texas, last year’s winner, rallied from the tail of the 20-car field to finish sixth while polesitter Jason Welshan of Maryville, Tenn., dropped out of the top five on the 11th lap and wasn’t a factor the rest of the way.

Sheppard jumped into the lead at the outset and never faced a serious challenge most of the race minus the rough spots that briefly bounced his car airborne. But as he navigated slower cars late in the race, he was certain he wasn’t turning laps nearly as quick as he’d been with clean racetrack.

“Man, it was crazy, because I knew that traffic was holding me up a bunch,” Sheppard said. “There’s no way to really tell how close (the pursuers) are. You can see a little bit on the (video) screen up there. Honestly, the last lap getting in here, I knew I was slowing down I was trying to pick the pace up.”

Sheppard hurried his way through the traffic the best he could, but Thornton gained on him every lap after taking the second spot from Nick Hoffman with 10 laps remaining. The winner may not realize how close Thornton came to taking a last-lap shot at him until watching the video after the race.

“Man, Ricky’s been tough all year. Congratulations to them guys on a phenomenal season,” said Sheppard, who dedicated the victory to his great grandmother who died earlier this week.

“I was able to go visit her this week while I was home, so that really was awesome and just got to see some of the family,” he said. “They knew that the Dome was this weekend, so I know this is where she would’ve wanted me to be, for sure.”

And the Dome’s victory lane is exactly where Sheppard wanted to be.

“An awesome clean race. It was nice and rough out there, just like the Dome likes it. So how about St. Louis? What did you think about that?” Sheppard asked the event’s biggest-ever crowd. “This crowd is phenomenal. Oh my God. I’ve never seen anything like it at a dirt track race. It's crazy to see all you fans in here, inside the Dome like this, it means the world to us drivers.”

Thornton started inside the second row but was running fifth at halfway. He eventually decided it was time to turn up the wick.

"I don't know, he was really good. I looked (at the scoreboard) and there was 11 (laps) to go, and I’m like, ‘Man, we didn’t come all the way here to run sixth.’ So I figured it was time to pony up and just get after it,” he said. “I had a good shot. I tried to (pull off a) slider on that last lap, but I knew I was gonna destroy him. I had to just kind of park it, and that kind of ruined any shot of winning it."

“I feel bad for my boys. I about destroyed the whole body in front of everything on this thing.”

Tanner English finished on the podium for the third consecutive year after starting outside the fifth row and breaking into the top five after 11 laps.

“We've been right there, two seconds, a third, should have won it twice, blew up, crashed … we've been knocking at the door for a long time,” English said. “I said this last year, I think, but I promise, one of these days I'm going to win this thing, and I hope this place erupts and maybe we can burn the place down. Hopefully (promoter) Cody (Sommer) don't end this deal any time soon and we can keep on coming back and maybe maybe get one of these.”

Notes: Nick Hoffman, who ran second the first 30 laps, slipped back late and blew a right-rear tire on the final lap with a huge piece of rubber flying off the racing surface and into the flagstand. He ended up ninth. … The 40-lapper was slowed by two cautions, the first when two-time race winner Tyler Carpenter slowed after getting into the frontstretch concrete and causing right-side damage. The second yellow appeared on the 17th lap when Chad Zobrist slowed on the frontstretch and pulled to the infield. … Zobrist and Carpenter were the lone retirees along with first-time Gateway starter Jimmy Owens, who had a flat tire after two laps.