NEW YORK >> Two days after undergoing season-ending Achilles surgery, Jayson Tatum had a chance to reconnect with his Celtics teammates.

Tatum, who remained in New York after suffering his injury Monday night, visited the team hotel on Thursday after the Celtics returned to the city for Game 6 of the Eastern Conference semifinals.

“It was really good seeing him,” guard Payton Pritchard said after Friday’s morning shootaround at Madison Square Garden. “Obviously, he’s out of surgery. He seemed like he was in really good spirits and stuff. Obviously, he’s probably about to be stir-crazy for a while now, but it was just good. When you see one of your brothers and one of your teammates going through a situation like that, you just want to be there to comfort him, anything he needs.”

Tatum will miss the rest of Boston’s playoff run — which the team extended Wednesday by winning Game 5 without their top star — and at least part of next season, as well. His father reportedly told ESPN’s Marc Spears that he expects the six-time All-Star to be out for “eight or nine months,” which would set him up to return in early 2026.

Asked how Tatum seemed, Pritchard said he was “in good spirits — as good as he can be.” He also said there wasn’t much talk about the current series during Tatum’s visit.

“We didn’t talk about basketball at all,” Pritchard said. “That stuff, it’s bigger than basketball now. It’s seeing how he is as a person, how he’s dealing with stuff. The basketball side, we’ll handle all that. But we just wanted to check in as a friend.”

Tatum sent a message to the team after his surgery, which center Luke Kornet described as him “just kind of encouraging us to go out and keep doing the job, keep trying to accomplish the goal.”

“It sucks to see someone like that go down that doesn’t deserve it,” wing Sam Hauser said. “But he wouldn’t want anything more than us to just keep winning. We saw him (Thursday), and he seems to be in good spirits. But we’re definitely thinking about him and just trying to get some wins for him.”

From an on-court perspective, the injury deprived the Celtics of their top scorer, rebounder and facilitator, as Tatum led the team in points, rebounds and assists per game this season (and in last year’s playoffs). They filled his void in Game 5 by pushing the pace, upping their ball movement and diversifying their offense while leaning on Kornet and his seven blocks to provide top-tier rim protection.

Derrick White led all scorers with 34 points, Jaylen Brown scored 23 with a career-high 12 assists and Pritchard added 17 points in 39 minutes off the bench as the Celtics won 127-102.

“With this unit we have, we should emphasize pace and getting up the floor,” Pritchard said. “We have a lot of people who like to play in open space and stuff like that. So this group will definitely push it. … Jayson is an unbelievable player. He’s an unbelievable player that can attack isolations and matchups, so when you have a stud like that, you take advantage of that. We don’t have that no more, so now we need to transition it to more pace, more off-ball, more stuff like that. It doesn’t mean that some of us aren’t capable of attacking; it’s just JT’s at a different level with that.”

Kornet starts

Kornet’s stellar Game 5 earned the Celtics big man a promotion.

Boston moved Kornet into the starting lineup for Friday night’s must-win Game 6 against the New York Knicks at Madison Square Garden. He replaced Kristaps Porzingis, who’s been limited by symptoms from a lingering viral illness since the start of the series.

Jrue Holiday, White, Brown and Al Horford rounded out the Celtics’ starting five.

Kornet blocked a career-high seven shots in Wednesday’s victory at TD Garden, including five in the third quarter to help the Celtics turn a tie game at halftime into a 25-point romp. The 7-foot-2 center also had 10 points, nine rebounds, one assist and one steal and was a plus-20 in 26 minutes.

Teammates used words like “huge,” “stellar” and “unbelievable” to describe Kornet’s Game 5 performance.

“He came in and just seemed to always be in the right position,” White said after that game. “Seven blocks is crazy. He was unbelievable tonight and really stepped up when we needed him. He’s had a great season and was big time for us tonight.”

Friday’s game was the first postseason start of Kornet’s eight-year career. The 29-year-old started 16 games this season (73 total appearances) and posted some of the best advanced metrics of any NBA player, including top-10 rankings in net rating, effective field-goal percentage and true shooting percentage. Among Celtics players, only Pritchard has posted a higher net rating than Kornet this postseason.

Porzingis sat out the second half of Game 5, with head coach Joe Mazzulla saying he “couldn’t breathe” and only would have reentered if the Celtics “absolutely needed him.” He was a minus-12 in his 12 first-half minutes, totaling one point, one rebound and two turnovers.

Mazzulla said before Game 6 that Porzingis “is playing” Friday night.

Thibs’ praise

The Celtics entered Friday with a 10-2 record in games Tatum missed this season, including two playoff wins. Knicks head coach Tom Thibodeau made a point during his pregame news conference to spotlight the talent Boston still possessed even with its centerpiece superstar on the shelf.

“Jaylen Brown, he’s an elite player in the league, so his role is always significant, but you have other guys who’ve had major roles previously in their careers,” Thibodeau said. “Like, when you look at what Holiday has done. And then overlooking a guy like Derrick White is a huge mistake, because he’s a great player and I think he’s recognized in the league. The same could be said for Horford. So you have to be ready for all the guys. Pritchard has had a monster year for them, and then Kornet has played really well for them, as well. And when Hauser comes in, he’s had a big year for them. So they have great talent on their team, and we have to be ready for that.”

Off the rim

Celtics reserve wing Torrey Craig supported Tatum by wearing one of his No. 0 armbands in each of the last two games. On Friday, Craig also repped a different teammate, arriving at Madison Square Garden in a No. 40 Kornet jersey.