Despite what head coach Joe Mazzulla called a “great” training camp, Lonnie Walker IV was unable to crack the Celtics’ regular-season roster.

Boston waived Walker on Saturday, according to reports from ESPN’s Bobby Marks and Shams Charania, choosing to leave their final 15-man roster spot open ahead of Tuesday’s season opener against the New York Knicks.

The experienced 25-year-old wing joined the Celtics on an Exhibit 10 tryout contract in late August after failing to land a guaranteed deal in free agency. Walker played in four of Boston’s five preseason games and saw extended action in two of them, tallying nine points, seven assists, four rebounds and two steals in 25 minutes against the Philadelphia 76ers’ backups and scoring 20 points on 8-of-15 shooting in a win over the Raptors. He was a DNP-CD in Tuesday’s preseason finale in Toronto.

Because the Celtics are well over the NBA’s luxury tax threshold, rostering Walker would have cost the team upward of $10 million between his veteran-minimum salary and accompanying tax penalties. He’s free to sign with any team, or could begin the season with the Celtics’ G League affiliate in Maine.

President of basketball operations Brad Stevens told Walker when he signed that a G League assignment was a possibility. Walker said early in training camp that he’d be “perfectly fine” with that outcome, despite the fact he hasn’t played in the NBA’s farm circuit since his rookie year in 2018-19.

Per the terms of his E-10 contract, Walker will receive a bonus if he plays a predetermined number of games in the G League.

Walker attended the Celtics’ Shamrock Foundation Tip-Off Gala on Friday night, then returned to Boston’s practice facility for a late-night workout, according to his Instagram. He was not present when the Celtics opened their doors to reporters after Saturday’s practice.

Mazzulla was mum on Walker’s status in his post-practice news conference, replying “I don’t know” when asked what the team planned to do with him. The report of Walker’s release came minutes later.

Throughout the preseason, Walker received praise from Mazzulla and teammates for his professionalism.

“He’s had a great approach,” the Celtics head coach said Friday. “(He’s) a guy that’s been around the league a long time and has seen different environments. He came in with his head down and just wanted to work and have an understanding of what it is to play our style of basketball at both ends of the floor.

“I thought he did a good job of executing that in the time that he had. I thought he did a great job being patient, executing the role we needed him to, and I thought he did a good job in the film room getting to an understanding of our system on both ends of the floor.”

Barring a late surprise, the Celtics will enter the season with 14 rostered players: Jayson Tatum, Jaylen Brown, Derrick White, Jrue Holiday, Kristaps Porzingis, Al Horford, Payton Pritchard, Sam Hauser, Luke Kornet, Neemias Queta, Jordan Walsh, Jordan Springer and Baylor Scheierman.

JD Davison, Drew Peterson and Anton Watson are on two-way contracts that allow them to split time between Boston and Maine.