The top team in the NBA will take the court Tuesday night at TD Garden. And it won’t be the Boston Celtics.

The Cleveland Cavaliers carry a flawless 15-0 record into the NBA Cup matchup on Causeway Street, setting the stage for a rare meeting between a reigning league champion and an opponent this hot.

It’s just the fourth time in NBA history and the first since 1996 that a defending champ faced off against a team riding at least a 15-game win streak, per ESPN.

“They’re good, man,” Celtics wing Sam Hauser said before Monday’s practice. “I just think they have a very similar group, and I think just having another year of chemistry and continuity together under your belt is important. And for them, it’s looked really good to this point. But we’re excited to try to put a loss in their loss column.”

Very similar, Hauser meant, to the Cavaliers team the Celtics dispatched in five games in last season’s Eastern Conference semifinals. Like Boston, Cleveland returned nearly its entire 2023-24 rotation, headlined by five-time All-Star guard Donovan Mitchell, who signed a $150 million contract extension this offseason.

The Cavs are led by a new head coach, however, with Kenny Atkinson replacing the ousted JB Bickerstaff. They’re also healthier at the top of their roster than they were in their playoff series against the Celtics, during which Mitchell missed two games and starting big man Jarrett Allen missed all five.

Cleveland rested Mitchell on Sunday — and lost rotation players Isaac Okoro and Dean Wade to ankle injuries — and still defeated the Charlotte Hornets 128-114 to become the fourth team in league history to start 15-0. Only the 2015-16 Golden State Warriors have opened a season with more consecutive wins (24-0).

“They’re crashing as a team, they’re cutting more as a team, opening up gaps for those guys to drive the ball, and they’re shooting the ball really well, all those guys,” Celtics head coach Joe Mazzulla said. “So yeah, they’re just playing at a high level right now, for sure. They’ve got a lot of talent, but I think some of the small tweaks that they’ve made in their cutting, their crashing and then just their ability to shoot the ball. And then their defensive versatility, too.”

Red-hot shooting from every area of the court has fueled the Cavs’ historic start. Atkinson’s squad entered the week ranked first in the NBA in both overall field-goal percentage (52.4%; no other team was above 50%) and 3-point field-goal percentage (41.2%; the only team above 40%). They’re also scoring the second-most baskets per game inside the restricted area, which could cause problems for a Celtics team that’s been less effective at defending the rim without rehabbing center Kristaps Porzingis.

As of Monday morning, Cleveland and Boston ranked first and second in the NBA, respectively, in both offensive rating and points per game.

“Obviously, they’re a really good team,” Celtics guard Payton Pritchard said. “They’ve got a lot of good guards, good length. I feel like their bigs are playing well. Obviously, their guards (Mitchell and Darius Garland, both of whom are averaging 20-plus points per game) are All-Star-level guards.

“So it’s going to be a good matchup. We’re looking forward to it. It’s going to be competitive, and hopefully the Boston crowd comes out (Tuesday night).”

The Celtics come in at 11-3 after downing the Toronto Raptors in overtime on Saturday. Every other Eastern Conference team entered the week with at least six losses.

Ultimately, the stakes for any NBA game in mid-November are relatively low. But Atkinson didn’t downplay the hype around this matchup.

“It’s great for the NBA,” Atkinson told reporters after Sunday’s Cavs win. “I think everybody’s going to be watching. I know our guys are anxious. I know they remember last year. We’re going well; they’re going well. Boston Garden. What’s better than that? It’s just great for the league, great for our franchise. We’re excited about it.”

The game also will have significant NBA Cup ramifications for Boston, which dropped its group-play opener against the Atlanta Hawks last week. Another tournament loss likely would put the Celtics out of contention for the knockout rounds, which will feature the winner of each of the six groups plus the top second-place finisher from each conference.

Each player on the team that wins the NBA Cup championship game in Las Vegas on Dec. 17 will receive a $500,000 bonus, with smaller playouts for clubs eliminated in the final, semifinals and quarterfinals.

“I haven’t paid much attention to (the Cavs’ record), honestly, but I think it is cool that they are undefeated, and coming into the TD Garden with the chance to put a loss in the loss column for them is going to be cool for us,” Hauser said. “It’s another big game with the NBA Cup stakes, and we obviously have to pretty much win out here to have a chance to go to Vegas. So it’s a really important game for us, and we’ll be ready to go.

Off the rim

Starting guard Jrue Holiday is expected to play against Cleveland, per Mazzulla. Holiday sat out the win over Toronto with a knee injury — the first DNP of the season for the 34-year-old. … With the Celtics idle on Sunday, Mazzulla took a trip to Portland to watch their G League affiliate. The Maine Celtics beat the Westchester Knicks 118-110 behind 31 points from two-way player JD Davison. First-round draft pick Baylor Scheierman added a 20-point, 11-rebound double-double to continue his strong start for the farm club. … The Celtics will make their traditional champion’s visit to the White House on Thursday, ahead of their Friday night road game against the Washington Wizards. “It’s exciting,” Hauser said. “You never know when an opportunity like that is going to come. It will be pretty cool to see, for sure, but try to get the job done here (Tuesday) first and worry about that later.” Mazzulla was asked whether he had any thoughts on the team’s impending trip to 1600 Pennsylvania Avenue. His response: “No, sir.”