AVONDALE, Ariz. — Cole Custer had all the makings for a successful defense of his NASCAR Xfinity Series championship from a year ago, leading the title-eligible quartet until Justin Allgaier’s late-race surge. Austin Hill also seemed to have a potential upper hand, out front for the final dash to the checkered flag after a late two-tire pit strategy play that put him in position for his first title.

Neither them nor fellow title contender AJ Allmendinger were able to capitalize in overtime in Saturday’s season finale, but all three were gracious in defeat as Allgaier drove to his long-awaited first Xfinity Series crown at Phoenix Raceway. Custer finished eighth, Allmendinger ninth and Hill completed the top 10 in the year-ending showdown, while Allgaier placed second behind race winner Riley Herbst.

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Custer’s bid seemed the strongest for much of the final stage, and he clung to the top spot among the Championship 4 foursome as the laps ticked down. His hold was challenged, however, as Allgaier rallied from a pair of penalties with a fortunate caution flag, then reeled in Custer’s No. 00 Stewart-Haas Racing Ford down the stretch. He slipped by for third place on Lap 194 of a scheduled 200 — extended 13 laps by a pair of overtimes — before a late caution shook up the situation.

Custer was jammed up when Hill tried to maintain his edge on older tires, giving Allgaier’s No. 7 JR Motorsports Chevrolet the edge for the last restart.

“Yeah, it definitely stings,” Custer said. “There were a lot of points in that race where I felt like we were in a really good spot here. But it just came down to that restart with the 21 (Hill) and him staying out on older tires, which is their right. We were all going for a championship, and I would have done the same thing. He made his car really wide going into Turn 1; so I tried to go high, I tried to go middle, and he ended up blocking us on the top and got us all bottlenecked. And then the 7 was able to slip by. You just get the short end of the stick sometimes, and that was us today.”

The attempt for back-to-back crowns was also a farewell for their Xfinity Series operation under the banner of Stewart-Haas Racing, which went out a winner with Herbst and a championship runner-up with Custer. No. 00 crew chief Jonathan Toney was magnanimous after the final flurry of restarts, tipping his cap to Allgaier after the checkers.

“It’s just coming down to that green-white-checkered here last year, the seas parted for us, and we were able to kind of come through the middle and be able to win the championship,” Toney told NASCAR.com. “Tonight, man, Justin’s come close so many times, and you can’t help but be happy for a guy like that and that team, (crew chief) Jim Pohlman, and that whole 7 bunch. That’s a championship-caliber team, and it’s been fun racing against them all year. You know, we’d love to win the championship for Cole, and we’ve got a lot of guys we’re going to be missing next year with this whole Stewart-Haas Racing going away this year. But we’re proud of this team. We’d love to win that championship, but the 98 (Herbst) winning this race, that was pretty cool, too. It kind of put an exclamation point on this season for our Stewart-Haas program.

“But yeah, you get in those situations. Last year, it went our way. This year, it didn’t. So you can’t be upset, this one corner or one race isn’t going to define our season. We’re proud of what we’ve done all year, and I think we proved ourselves as a championship-caliber team. At the end of the day, that’s all you can ask for.”

Hill led just once for five laps, but those were in overtime after crew chief Andy Street went with two tires — a half-set of seven-lap-old scuffs — on the No. 21 Richard Childress Racing Chevrolet, putting Hill up front on Lap 201. The tire disadvantage showed when the race went back green, and Hill’s move to block the top side only worked so long, shorting Custer’s momentum and providing an avenue for Allgaier to move low and clinch.

“It was kind of a Hail Mary shot there at the end,” Street said. “But I had confidence in Austin that if we got track position up there, he could make the car pretty wide. But it was gonna be hard to hold off any kind of stickers (new tires) behind us.”

The result brought an end to Hill’s first Championship 4 appearance and a season where he collected a series-high four wins. He’ll return to RCR’s No. 21 group next year.

“Obviously, you want to win the championship, so we came up short there,” Hill said. “But all in all, I think at the start of February in Daytona, you just want to be one of those final four drivers to have a shot at it. We were able to do that. I think all in all, this year has been a solid year for us. There’s areas that we still need to work on and be better as a race team, some other areas to win some more races. I think that we’re going to be a lot better going into next year. There’s a lot of things going on at RCR with new cars and just some moving parts and pieces. I feel really good about where I’m at with RCR. I think we’re making strides each and every year, and if we keep doing that, we’ll end up a champion one day.”

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Allmendinger officially finished where he started — in ninth — but his No. 16 Kaulig Racing Chevy was relegated to the tail of the field for the start because of unapproved pre-race adjustments. He came back up through the field along with Allgaier in the early going, and he was 18th at the end of the first stage, bringing up the Championship 4 caboose. He’d come back to seventh by Stage 2’s end, but never quite forged his way into the field’s top rungs.

“I told my guys before the weekend started that I wouldn’t pick any other guys to go to war with like we did,” Allmendinger said. “We’ve had a lot of ups and downs. At times maybe not enough speed. At times, maybe me trying to push too hard. I was happy I could at least get them a win at Vegas. I feel like I’ve let them down a lot of times this year. Yeah, today was disappointing. I’m not sure what else we can do from a preparation and effort standpoint, honestly. We spent three weeks working on the car and countless hours in sim. Just was never there all weekend, honestly. Just fought hard.”

Allmendinger sat on the pit wall for several minutes after parking. He’ll return to the Cup Series full-time next year after achieving his second Championship 4 appearance in the last four seasons.

“We struggled finding a good balance for AJ to make speed with,” No. 16 crew chief Alex Yontz told NASCAR.com. “So having to start in the rear, for sure didn’t help anything, but at the end of the day, I don’t think it changed the outcome of where we finished, how we raced. All we could ask for was that late caution and to get tires there and just have a shot at it. Can’t say enough about all the men and women at Kaulig Racing for working their butts off all year and giving us this opportunity and putting us in position to race for a championship.

“We’ve been here, I think, a total of three times now, four with Kaulig, and I feel like we’ve walked away each time learning something else new. So for us to still be a smaller, newer team, I feel like we’re on the right track. We didn’t come home with the championship, but we’re not going to hang our heads. We’re going to walk out of this garage with our heads held high, just the same way we did when we walked in. No, we didn’t win it, but we give it one hell of a shot.”