Busch passed Elliott on the final lap of the Apache Warrior 400 for his fourth win of the season and second in the three-race first round of the 2017 playoffs.
"It's, no doubt, the moment that you live for," Busch said. "It's the moment that all these guys live for and what we do with this M&M's Caramel team, and this Toyota Camry was not the best there early on, but we made a lot of gains on it and got it where it was really good there at the end.
"And I was making the most out of it, there, and being able to run the top and get some speed going with some momentum around the top side, and I can't say enough about Chase. I mean, he's an awesome competitor and great kid, great friend. I raced with him in late models, and coming off of (turn) two, there, you know, he could have pulled up and checked up my momentum.
"I did kind of checkup, because I wasn't quite sure, but then, he gave me enough room, and I put it back down and just kept my momentum up there, got along side of him and got ready for the entry to (turn) three."
"I'm just so disappointed in myself," Elliott said. "Golly, I couldn't have had it any easier. It ran green from the stage break all the way to the end, and I gave it away. I appreciate my team and their efforts today. The pit stops were great and they kept us in the ballgame. I didn't."
Elliott led most of the 160 laps that made up the third stage of the race, taking the lead on the restart at the beginning of the final stage when previous leader, Larson, bobbled because of a power issue.
"It was a really good race," Larson said. "I won that second stage and was the leader off pit road, and then my engine was kind of struggling firing up when I would cycle the engine and cool it down under yellows. It just didn't re-fire that one time and had to restart fifth and fell back to sixth.
"Kind of hard to pass when I got back there. I couldn't really move up the race track, because I would be in dirty air. We short-pitted, got to third, but fell back and finished fifth. I felt like, if I could have restarted the leader, I probably would have had a shot to win like the No. 24 (Elliott), but once I had restarted on the inside of the third row, I was kind of done unless I had a caution, which there wasn't any left the rest of the race."
Ryan Newman managed to stay just in front of the leaders in the closing laps to finish on the lead lap, but still, he fell one point shy of displacing Ricky Stenhouse Jr., who wasn't on the lead lap, in one of the 12 advancing playoff positions.
Newman missed advancing by two points, and his Richard Childress Racing teammate, Dillon, wound up four points shy of playoff advancement.
"The feeling is lucky, really," Stenhouse said. "We caught the caution, there, right at the right time with a perfect amount of laps left in the stage to get stage points and that was the turning point of the day. Our Fastenal Ford was, definitely, not close to what we needed, especially the last two runs.
"We were close before the last two runs and made some adjustments, there, and really fell off. All in all, like I said, I feel lucky that we had all the mistakes at Chicago and really not a good car at Chicago, Loudon or Dover, but we still made it in. Really, it is hats off to the guys for fighting all day and it is nice that the round starts over."
Larson and Truex Jr. combined to lead most of the first two stages that made up the first 240 laps of the 400-lap race. Larson won the second stage, but Brad Keselowski won stage one.
Keselowski was one of only five drivers who still hadn't pitted when the yellow flag, followed by a red flag, waved for the first time on lap 87 for a Jeffrey Earnhardt wreck at the entrance of pit road that damaged a barrier of sand barrels.
After everyone but Keselowski, Kyle Busch, Stenhouse, Danica Patrick and David Ragan already had pitted under green, those five drivers were the only ones on the lead lap when the yellow waved. Previous lead lap cars got back on the lead lap with a wave-around.
When the race restarted, Truex quickly got up to third and Larson sixth by the end of the first stage.
Busch got off pit road first to restart the second stage with the lead, but on lap 141, Larson got by him for the top spot and Truex took second.
NOTES: Ryan Blaney dominated and won the NASCAR Xfinity Series race at Dover International Speedway on Saturday. ... Jimmie Johnson is the all-time winningest driver at Dover with 11 Monster Energy NASCAR Cup Series wins, including the most recent race at Dover in June. Kyle Busch has 11 wins across all three NASCAR national series at Dover, including two in the Cup Series. ... Martin Truex Jr. won last year's playoff race at Dover. ... Austin Dillon, Ryan Newman, Kurt Busch and Kasey Kahne were the bottom four playoff drivers in the standings, heading into the Apache Warrior 400, the first elimination race of the 2017 playoffs, but Dillon was tied with Ricky Stenhouse Jr. for the 12th position, the last advancing position, in the standings. ... Truex and Kyle Busch secured advancement to the second round of the playoffs with wins in the first two playoff races at Chicagoland Speedway and New Hampshire Motor Speedway. Kyle Larson and Brad Keselowski also were locked into the second round ahead of the Dover race by virtue of their position in the points standings ... Third-place qualifier, Larson, was the only non-Toyota driver to start in the top six for Sunday's race.