OKLAHOMA CITY -- Rookie center Chet Holmgren unzipped his black hoodie sweatshirt when asked how the Oklahoma City Thunder celebrated earning the Western Conference's No. 1 seed, showing off his blue Northwest Division champions T-shirt that was handed out in the locker room.

The Thunder took a team picture to commemorate the occasion after Sunday's 135-86 win over the Dallas Mavericks -- who rested all their starters and a few key reserves -- then shifted their focus to preparing for the playoffs.

"I wouldn't say celebratory so much as just kind of recognizing the fruition of all the hard work that we've been putting in," Holmgren said. "We're not in the position we're in by accident. There was a lot of dedication and hard work that went into it.

"But we're not celebrating, because what we're trying to do, we're not there yet. So, we're still eyes on the prize, locked in."

Oklahoma City entered the final day of the regular season in a three-way tie for first place in the West with the Denver Nuggets and Minnesota Timberwolves, the first such occurrence in NBA history. The Thunder finished with a 57-25 record, as did the defending NBA champion Nuggets, but Oklahoma City owned the tiebreaker.

As a result, the Thunder are the youngest team to earn the No. 1 seed since seeding began in 1984, according to ESPN Stats & Information research. Oklahoma City has an average age of 23.9 years old, weighted by playing time, which is almost two years younger than that of the 2004-05 Phoenix Suns, the previous youngest 1-seed.

The Thunder made the jump from a 24-win lottery team to the West's top seed in only two years.

"It's super surreal. It's fun," said Thunder superstar Shai Gilgeous-Alexander, Oklahoma City's oldest starter at 25. "Obviously, you play to win. It's [more fun] like that, but I think it goes back to us chipping away at it every day and not worrying about the past or the future. Just chipping away, seeing where that gets us, and us taking that mentality has allowed us to get here.

"So, yeah, it feels good, something to be proud about. We have a lot more work to do."

Oklahoma City and Denver will await the results of the West play-in games to learn who they will face in the first round of the playoffs. The second-seeded Nuggets will play the winner of the Nos. 7-8 game between the New Orleans Pelicans and Los Angeles Lakers. The loser of that contest will play the winner of the Nos. 9-10 game between the Sacramento Kings and Golden State Warriors to determine the Thunder's first-round opponent.

The Timberwolves dropped to the third seed after their 125-106 home loss to the Suns on Sunday. Phoenix's win, combined with New Orleans' 124-108 loss to the Lakers, allowed the Suns to claim the sixth seed and avoid the play-in. Minnesota and Phoenix will meet in the first round.

The LA Clippers and Mavericks entered Sunday locked into the fourth and fifth seeds, respectively, and they will face each other in the first round. It will be the third time that MVP candidate Luka Doncic has matched up against Kawhi Leonard's Clippers in the first round, with LA eliminating Dallas in both of the previous series.

Denver's two-time MVP Nikola Jokic, Doncic and Gilgeous-Alexander are considered the top candidates for this year's honor.

"I don't study all the players. I do see one of them every single night." Oklahoma City coach Mark Daigneault said, referring to Gilgeous-Alexander, who averaged 30.1 points, 6.2 assists and a league-leading 2.0 steals per game. "There is not a night where I don't feel like we have the best player on the floor. We're a top-five defense, top-five offense. He's a two-end player that contributes to both of those things.

"I think his consistency, his poise, his confidence has had an unbelievable contagious effect on one of the youngest teams in the league, one of the youngest teams in history to accomplish what this team accomplished. ... When you look at what he did this year, what seeds he's planted in previous years, there's no one I'd rather have on our team than him."