BOSTON (AP) — Jayson Tatum was already a proven winner before last season.

In Tatum’s first six seasons, no NBA player won more games with one team than he did. Tatum played in 334 wins with the Boston Celtics over that span, including playoffs. He was a five-time All-Star, a legitimate MVP candidate, a four-time All-NBA pick, even an Olympic gold medalist.

He just wasn’t a champion.

“I had to listen to all the (stuff) that people said about me,” Tatum said.

That’s all in the past now. The Celtics are champions, coach Joe Mazzulla leading them to that crown, and when the season starts on Tuesday night, Oct. 22, in Boston — where last season ended — Tatum doesn’t seem to be considering it the start of a title defense. He’s looking at it as the start of a chase for a 19th title, and according to BetMGM Sportsbook, the Celtics are the favorite to claim the 2025 championship.

“It was never just about trying to just win one,” said Tatum, who added a second Olympic gold to his collection this summer. “Now you get to be mentioned with — at least be in the same room with — the other Celtics great teams, great players. All the guys that I looked up to growing up at least won one championship. Now it’s just a conversation of: ‘How great are you trying to be? What room or what tier are you trying to be mentioned in when it’s all said and done?’”

That journey starts with ring night in Boston, where the Celtics take on New York in the first game of a doubleheader to formally open the league's 79th season. The nightcap is Minnesota at the Los Angeles Lakers, a game that will see LeBron James tie Vince Carter by playing in a 22nd NBA season — and potentially the first official game where a father and son are teammates, with Bronny James entering his rookie season.

There will be challengers to a Boston repeat, and a lot of them. New York (adding Mikal Bridges and Karl-Anthony Towns) and Philadelphia (adding Paul George) loaded up to try to supplant Boston atop the Eastern Conference. And there are rising teams in the East as well, like the Paolo Banchero-led Orlando Magic and Donovan Mitchell-led Cleveland Cavaliers — who made Round 2 of the playoffs last season.

“We've just got to keep our foot on the gas,” Mitchell said. “We've got to keep going.”

And the Western Conference also has several contenders.

BetMGM has Oklahoma City — the No. 1 seed in the West last season, led by MVP hopeful Shai Gilgeous-Alexander — as the narrow favorite to win that side of the league, with 2023 NBA champion Denver, reigning West champion Dallas and a Minnesota team that went to the West finals a season ago all in the mix.

“You have to be careful with expectations put on outcomes,” Thunder forward Chet Holmgren said. “Around here we really emphasize putting expectations on processes, how we show up every day, how we go about our work, what we do, and the attention of detail that we do it to. That’s what we’re really focused on.”

Golden State's Stephen Curry helped the U.S. win Olympic gold this summer; the Warriors can never be counted out. And with James, neither can the Lakers.

“We’re the hunters, amongst many other teams,” Curry said. “What can this team do to maximize every skill set that we have in that locker room? That’s the challenge for us.”

The West is just loaded. But these Celtics — who return virtually intact from a year ago — know what it takes to be the last team standing.

“Boston can say whatever they want to say. They’ve earned it. They beat all of us and they were crowned,” Miami coach Erik Spoelstra said. “So, they can feel however they want to feel going into this season. With that said, (they) still have to earn it. But it’s a new season, new year. There’ll be a bunch of teams that are gunning for that title.”

Meanwhile, the Celtics are giving themselves one more chance to celebrate their latest NBA championship before they turn their attention to a repeat.

The league’s most decorated franchise will raise its 18th banner to the TD Garden rafters Tuesday night before the season opener against the New York Knicks. Players will also receive their championship rings in the pregame ceremony.

“This is a great accomplishment, that we get to do this. Be one hell of a night,” guard Payton Pritchard said after practice Monday. “But then again, we talked about we’ve got to do it again. We’ve got to reset that focus.

“We get the rings, and then we want to go out and prove that we’re ready to make another statement.”

The Celtics cruised through the NBA regular season last year — finishing with the best record in the Eastern Conference by 14 games — and then went 16-3 in the playoffs. Led by Jayson Tatum and Jaylen Brown, they are bringing back their entire starting lineup and most of their bench, and are the favorites to win it all again.

Coach Joe Mazzulla has said he doesn’t feel any pressure to repeat.

“We’re all going to be dead soon, and it really doesn’t matter anymore. So there’s zero pressure," he said. "You have an opportunity to carry the organization forward, to double down on the tradition and history of what this organization has. And what else would you expect than someone expecting you to win all the time?

"It’s not pressure,” he told reporters at the team's practice facility. "There’s nothing anyone in this circle can do to me that’s gonna impact my identity and who I am as a person or a coach. We’re either gonna win or we’re not, and 40 years from now, none of you are invited to my funeral and that’s it.”

The Celtics won 16 NBA titles from 1957-86, with Bill Russell claiming 11 in 13 years. The 1970s teams of Dave Cowens and John Havlicek won a pair, and the Big Three of Larry Bird, Robert Parish and Kevin McHale won three more in the 1980s.

When Paul Pierce, Kevin Garnett and Ray Allen won it all in 2008, they ended the franchise’s longest-ever title drought. They made it back to the NBA Finals two years later, but lost to the Lakers. (The period from 2008-24 was the second-longest drought.)

Pritchard said that to be considered among the Celtics greats they will need to win another.

“A lot of people can do it once," Pritchard said. “I know a championship’s hard, but there’s a lot of people who have won one. But winning it multiple times, creating almost like a dynasty, that’s hard to do. So that’s greatness, and that’s something we’re trying to achieve.”

The quest begins against the Knicks, who have positioned themselves as Boston’s top competition in the East after acquiring Karl-Anthony Towns and Mikal Bridges over the summer.

Mazzulla said he thinks his team will be ready.

“I trust who they are. I think they have an understanding of both ‘This is what we accomplished’ and ‘This is what we’re trying to do’” the coach said. “All the intangibles that go into winning should carry over from one season to another season."

“You have to appreciate it," he said. "But you’ve got to know what got you there and if you forget what got you there, you’ll never get back.”