Five months after their 2025-26 season ended with a first-round faceplant against the 76ers — and three months after they traded franchise pillar Jaylen Brown to that same Philadelphia squad — the Celtics will make their return to game action Thursday night in Cleveland.
The 159-day gap between Game 7 against the Sixers and Boston’s preseason opener against the Cavaliers at Rocket Arena matches the longest between any Celtics games since 2016, according to the team’s radio play-by-play voice, Sean Grande.
During that break, the Celtics radically retooled the top of their roster by shipping out Brown in a controversial trade and recentering the team around Jayson Tatum, who is preparing to play his first full season since undergoing Achilles surgery in May 2025. Trade acquisition Paul George and free agent signee Mitchell Robinson are expected to fill vital roles for this new-look group, with 20-year veteran Mike Conley also coming aboard to provide leadership and backcourt depth.
Will we see all of Boston’s key pieces on the court against the Cavs? That’s not yet clear. Last year, head coach Joe Mazzulla sat multiple regulars in each of the first two preseason games and didn’t field his first-choice starting lineup until opening night. (Mazzulla then changed that lineup a week later, and several more times throughout the season.)
With that in mind, here are five things to watch in Thursday’s exhibition:
1. 100% Tatum?
The last time we saw Tatum in a game setting, he was watching from the bench in an all-gray jumpsuit as the Celtics lost Game 7 at home.
The injury that kept Tatum out of that season-deciding defeat — the team called it “left knee stiffness” — underscored the fact that he never made it back to full strength after his early-March return from surgery. The perennial All-NBA wing estimated he was playing at “80 to 85%” of his capacity, which was evident even as he posted impressive numbers for a player in his situation (22-10-5 in 16 regular-season games).
How will Tatum look now that he’s banked another five months of recovery time and had a full summer to improve his conditioning and explosiveness? His health will, quite obviously, be of paramount importance for the Celtics as they move forward without Brown.
Celtics stars Jayson Tatum, left, and Paul George pose for photos during media day on Sept. 28. Nancy Lane/Boston Herald
2. How do the new guys fit?
George, who likely will slide into Brown’s old spot in the starting five, has made clear since his arrival that he is not trying to be an Option 1B to Tatum’s 1A. The 36-year-old views himself as a member of Tatum’s supporting cast, saying he plans to do all he can to make life easier for Boston’s “superstar.”
How will that manifest on the court? How will the Celtics’ offense change stylistically with George — who was a highly effective secondary option against Boston in last season’s playoffs — replacing the higher-usage Brown? Who will take on the second-largest offensive load: George, or someone else like Payton Pritchard?
Elsewhere, how will Mazzulla, who’s long admired Robinson’s game, integrate the former New York Knick? And how will his presence affect last season’s starting center, Neemias Queta? Queta told reporters Tuesday that he’s worked on becoming more of a shooting threat (he’s made just one career 3-pointer), so that’s something worth monitoring.
3. Which wings?
One of the Celtics’ biggest strengths in 2025-26 was their deep well of dynamic wings, who wore down opponents with their energy and helped Boston become a top-five rebounding team through constant glass-crashing.
Outside of Brown, every member of that group is back this season. And there likely won’t be enough minutes for all of them when the Celtics have their full roster available.
Will any of Baylor Scheierman, Sam Hauser, Hugo Gonzalez, Jordan Walsh and Ron Harper Jr. separate themselves this preseason? How will that hierarchy — which is bound to evolve based on matchups, performance and player availability — look when the regular season opens on Oct. 20?
If Mazzulla has reservations about starting Pritchard, as he did in the back half of last season after the Celtics traded away third guard Anfernee Simons, then his fifth starter likely will come from this quintet.
4. Rookie preview
Draft picks Chris Cenac Jr. and Dillon Mitchell both impressed at the Las Vegas Summer League back in July. How will they look against real NBA competition?
Cenac, a 6-foot-11 center out of Houston and Boston’s youngest player (19), has drawn high praise from some of his fellow Celtics bigs. The highest came from Queta, who said Cenac can be “a juggernaut in this league” with his blend of size, athleticism and versatility.
Mitchell, another high-end athlete who excelled as a perimeter defender at St. John’s, believes he’s improved his poor 3-point shooting under the direction of Celtics director of player development Craig Luscenat. He is on a two-way contract; Cenac’s is a standard deal.
Given the depth in their respective position groups, both are more likely to see minutes in Maine than Boston as they begin their pro careers. But that was also the expectation for Gonzalez at this time last year, and he went on to appear in 74 games as a rookie.
5. Tryout auditions
The Celtics have five non-roster players competing for their final open two-way contract slot: guards Devin Carter, Hayden Gray and Milos Uzan, and forwards Gabe McGlothan and Tucker DeVries.
Carter is the biggest name in that group. He starred at Providence College and was drafted 13th overall by Sacramento in 2024. After two unremarkable seasons, Carter was traded to Atlanta and quickly waived, leading him to sign an Exhibit-10 tryout contract with Boston as he looks to keep his NBA career afloat.
It’s a humbling position for a recent lottery pick, but Mazzulla said Carter has approached training camp with the right attitude.
“He’s very open about wanting to make it,” Mazzulla said last week. “So I’ve appreciated just his mindset, his mentality, the chip on the shoulder that he brings to the game. I’m looking forward to watching him throughout the preseason.”
Keep an eye on how Carter and the rest of the E-10s are deployed Thursday night. In last year’s preseason opener, Harper was the only tryout player to check in before the fourth quarter; two weeks later, he landed a two-way contract.