Kurt Busch out-dueled his younger brother Kyle Busch in the pair's fourth career 1-2 finish to secure his 2021 NASCAR Cup Series Playoffs position and take his 33rd career victory in Sunday's Quaker State 400 Presented by Walmart.

Busch, 42, has been particularly good at the 1.5-mile Atlanta Motor Speedway. Sunday's win was his fourth there, most among the current field, and the last trophy given before the historic NASCAR track is repaved and reconfigured going forward.

More importantly Sunday's work was a big statement for Busch, who started the race with only a 25-point buffer in the championship standings with six races left to set the 16-driver Playoffs field. Now with the win, he's "in" and his emotions climbing out of Chip Ganassi Racing's No. 1 Chevrolet certainly reflected the relief and joy.

He simultaneously earned a Playoffs position and evened the score with his brother – each have won two races in the four times they have finished first and second.

"Hell yeah, we beat Kyle," a smiling Kurt Busch said after climbing out of his car, putting his fists in the air and turning toward the cheering crowd in the grandstands.

"What a battle on an old-school race track," said Busch, who has 33 career NASCAR Cup Series wins.

"It's been one of those years where I knew we were going to have our back against the wall, just above the [Playoffs] cut-off line and needed to race hard and race smart."

Not too surprisingly, Kyle Busch's mood standing by his car on pit lane was markedly different than his brother's. He felt like Kurt's Chip Ganassi Racing teammate Ross Chastain interfered a bit as the two brothers were fighting for the race lead while navigating lapped traffic.

Kurt led a race high 144 of the 267 laps – the most he's led in a single race since 2015 (291 laps at Richmond, Va.) and the two each won a Stage. Kurt came out behind his brother on track when the final round of pit stops cycled out, but ultimately passed Kyle for good with 25 laps remaining and crossed the finish line 1.237 seconds ahead of his brother. Kyle was able to pull alongside Kurt with seven to go, but unable to make the pass in lapped traffic.

"I gave everything I had there early and then just smoked it behind the 42 [Chastain] obviously, shows you what kind of driver he is," Kyle Busch said.  "Just trying to fight hard after that when I got passed.

"Great effort, the guys gave me a great piece," Kyle continued. "The 1 (Kurt Busch) was definitely better than us today, I just thought I had him."

Kyle's Joe Gibbs Racing teammate Martin Truex Jr. finished third, rallying from a 37th place starting position. Hendrick Motorsports driver Alex Bowman was fourth followed by Penske Racing's Ryan Blaney, who won at Atlanta this March.

Tyler Reddick, Georgia native Chase Elliott, Christopher Bell, Matt DiBenedetto and Brad Keselowski rounded out the Top-10.

Noticeably absent from that group is the series' only four-race winner Kyle Larson. He ran among the top five for most of the race, but was penalized for speeding on pit road during his final pit stop. He instead finished 18th.

Championship points leader Denny Hamlin, who is still looking for his first win of 2021, finished 13th. He also was handed a pit road penalty early in the race, which was red-flagged for about 20 minutes just after the completion of Stage 2 so track workers could repair the track surface.

The series moves to the New Hampshire Motor Speedway 1-miler next week for the Foxwood Resort Casino 301 (3 p.m. ET, NBCSN, PRN, SiriusXM NASCAR Radio).

With five races remaining to set the 16-driver Playoffs field, 12 drivers have now earned automatic bids with a race victory. Hamlin, Kevin Harvick, who rallied to an 11th place finish Sunday, Austin Dillon and Reddick are the four highest-ranked drivers on points.