Custer held off Logano on Saturday at Chicagoland Speedway for his fourth NASCAR Xfinity Series victory of the season.
The 21-year-old Custer had the strongest car all day, leading 151 of the 200 laps for the 300-mile race. But he had to rally after Michael Annett and Noah Gragson stayed on the track while the leaders went for a pit stop, and then he benefited from a timely caution when B.J. McLeod got into the wall.
No big deal for Custer, who zoomed into the lead on a restart with about 21 laps left. He stayed in control the rest of the way on a hot, humid day in suburban Chicago, securing his sixth career victory.
"We were so fast, I wasn't that worried about it," Custer said. "It was just a matter of, I knew we were probably going to get by them because we were the fastest car, especially compared to them all day. It was just a matter of, I didn't want [Logano] to get to the lead before me, because then I would have been in his dirty air."
Logano took second in his first Xfinity Series start since he finished fifth at Bristol on Aug. 17. Logano is considered one of the favorites for Sunday's Cup series race on the bumpy 1.5-mile oval.
He praised Custer after the race, saying he was ready for the next level.
"I mean, that's huge," Custer said. "Joey's a series champion and it was fun racing with him today. I think we had the better car. I think that was a huge part of it. But I think at least I didn't make any mistakes."
Custer, Christopher Bell and Tyler Reddick have been battling for control of the series all year. Bell crossed the finish line third, but his championship hopes took a hit when he was disqualified after his car failed a postrace inspection.
Wayne Auton, the managing director of the Xfinity Series, said Bell's No. 20 Toyota was too low in the front and too high on the right rear side of the car. Joe Gibbs Racing has until Monday to appeal the decision.
Things happen, and we feel 100 percent confident that we did our job the way we do every car,'' Auton said. "We checked every car the same way. We had five other cars that went right through the same process at the end of the race, including the winner.''
Custer's No. 00 Stewart-Haas Racing Ford had one lug nut that wasn't safely secured, but that infraction doesn't affect his finish. He moved into a tie with Bell for the lead in Xfinity wins.
Reddick, who is on top of the series standings, was ninth.
"All in all, this is where we need to be,'' Jones said. "We had great stages. Great points day -- it's what we need to do to get back into this thing."
Justin Allgaier, who grew up in Riverton, Illinois, and calls Chicagoland a home track, hit the wall twice in the last part of the race and did not finish. He remains winless on the year after earning five victories last season.
Logano began the race in front after earning his 36th career Xfinity Series pole. But Custer quickly took over and won Stage 1, followed by Reddick, Bell and Jones.
Adjusting quickly to the different Xfinity Series car, Logano moved into the lead in time to take Stage 2. Logano led three times for a total of 20 laps.