BOSTON (CBS) — Kemba Walker is pretty bummed that he won’t be starting the 2020-21 season with the rest of his Celtics teammates. The point guard will sit out the opening weeks of the new campaign in the hopes that his balky left knee will get better with more rest.

Walker, as always, was his upbeat and jovial self when talking about his health situation with Boston reporters on Wednesday. But his disappointment was evident as he spoke about his near future.

“This sucks,” Walker said bluntly during his Zoom session with reporters. “But I also love the game of basketball and I want to play at a high level for the fans who watch this game. I want to be at my best. Last season in the playoffs, I wasn’t at my best and it sucked. I don’t want to be that way no more.”

Walker spent the offseason trying to figure out the best way to treat his bothersome knee, and after getting additional opinions from two other doctors, all parties involved decided that stem cell injections into the knee and a 12-week strengthening program were the best path to a recovery. It will keep Walker out until at least the early parts of January, but he is confident that he’ll be able to return to his old self when it’s all done.

“We decided not to rush back, take my time and get healthy. I’ve had a pretty long run; haven’t had much of a break since I signed here. It will be nice for me, to tell you the truth,” said Walker, who played in the FIBA World Cup last offseason ahead of his first season in Boston.

As for the injections, Walker was pretty honest when asked if he could explain exactly what they’ll do to his knee,

“I can’t. I don’t know. You have to ask the doctors,” he chuckled. “It’s supposed to help me, I know that. A lot of good stuff for the knee. I just went into it, I trust the doctors and I trust the people who are helping me. It was the best way to go and it has definitely calmed my knee down a lot.”

There are no benchmarks that Walker is looking for in his recovery. He said that he’ll just know when things return to normal.

“The way I felt the last couple of months, if I don’t feel that way then I’m better. It wasn’t good,” he said. “I wasn’t myself. It’s really just about being comfortable, 100 percent comfortable when I’m making my moves and not having any thoughts or thinking there is going to be pain when I land. That will be the signs of me feeling good again.”

While Walker sounded mostly upbeat on Wednesday, his knee situation remains a giant concern for the Celtics. He missed nine games with the injury last season before COVID-19 put the season on pause, and even after that months-long break, Walker was brought back slowly when the team made its way to the Orlando bubble. Even with the Celtics taking it slowly with Walker, he went on to have an uneven postseason for Boston. Overall, Kemba was fine, averaging 19.6 points off 44 percent shooting, but something was clearly off in Boston’s march to the Eastern Conference Finals. He struggled mightily against the Raptors in the East Semis, and was ignored at the three-point line for much of the playoffs, hitting just 31 percent of his attempts from downtown.

Now, after a four-month offseason, he still needs more rest to try to get back to being Kemba. It’s all a bit worrisome.

But it’s in Boston’s best interest to have Walker healthy come May and June, so the Celtics are fine with letting him sit out some games in December and January. Danny Ainge brought in veteran point guard Jeff Teague to help with Boston’s depth at the position, and he may find himself starting games for his new team when the season tips off Dec. 22.

Despite the Celtics losing Gordon Hayward via free agency, Walker is excited for the season ahead. He hopes that the additions of Teague and Tristan Thompson, along with the progress of Boston’s young stars, will help get the Celtics to the Finals.

“I think we got better, especially adding Tristan [Thompson] and Jeff. They’ll help us big time,” he said. “But who knows, anything can happen. We’re going to put in the work to get to where we need to be. That’s what is most important, us getting better throughout the year and staying together when things get tough. It’s all about what you do through adversity. If we can stay together, that will get us over the hump we need to get over.”

Without Walker, the Celtics will have plenty of adversity to battle early in the season.