Mayer was among a handful of cars that were trying to stretch their fuel without a final pit stop but found himself in the danger zone as the race went into a two-lap overtime.
As the field entered Turn 2, Mayer wheel-hopped and got into Gibbs, which sent him spinning off course and allowed Creed to move into the lead.
Mayer then ran down Creed to take the lead and spent the final lap holding him at bay before taking the checkered flag by 0.909 seconds.
The win is the second of Mayer’s career, with both coming in the last four races and both coming on road courses (the other was Road America).
“The first restart, I got used up and thought I had a good one there. We had to work our tails off for this,” Mayer said. “We earned this one, for sure.
“I wheel-hopped it. It’s unfortunate. I feel bad for doing that, obviously. I don’t want to take out a Gibbs car like that, or any car like that. Just trying to get another win in the Xfinity Series. I mean I got a lot of catching up to do.”
Gibbs was looking for his second straight win and led 70 of the 86 laps before he was hit by Mayer.
“When you have to race out of desperation like that and you wheel-hop and clean the leader out, I guess it’s a part of racing, but it just really sucks,” Gibbs said. “We had a great time out there. I definitely wish that (last) caution didn’t come out there.”
Parker Kligerman rallied to finish third, Ross Chastain was fourth and Connor Mosack rounded out the top five.
Completing the top-10 were John Hunter Nemechek, Cole Custer, Chandler Smith, Alex Bowman and Jeb Burton.
Stage 1
With the completion of lap 20, Gibbs held a more than four-second lead over Justin Allgaier and picked up the Stage 1 win. Mayer was third, Josh Berry fourth and Austin Hill rounded out the top five.
Busch was forced to pit under green for a flat tire while Chandler Smith, Jeremy Clements and Mosack all briefly went off course during the stage but were able to continue in the race.
Stage 2
With the completion of lap 40, Gibbs held a nearly three-second lead over Bowman to claim the Stage 2 win. Hill was third, Allgaier fourth and Custer fifth.
While the race was under caution for a stalled car, Josh Williams plowed into the back of Stefan Parsons, doing extensive damage to his No. 92 car and knocking him out of the race.
“That’s my fault. I was plugging my headphones in,” Williams said over his team radio. “It’s the dumbest (expletive) I’ve ever done in my entire life.”
Stage 3
With 20 laps remaining, Gibbs had built a more than three-second lead over Hill as Bowman and Custer battled for third.
Gibbs hit pit road for fuel-only with 10 laps remaining, which handed the lead over to Mayer, who had been saving fuel. After his stop, Gibbs cycled into the fifth position, about eight seconds behind Mayer.
Parker Retzlaff got stuck in the gravel pit off Turn 6 which forced NASCAR to display a caution and set up a restart with four laps to go. Mayer remained out front.
Gibbs grabbed the lead back on the restart and a multi-car wreck erupted behind him as the Allgaier got turned around exiting the bus stop. Bowman, Brandon Jones, Kaz Grala and Sage Karam were also collected in the incident.
The wreck sent the race into a two-lap overtime with Gibbs out front followed by Hill, Mayer, Custer and Kligerman.