By Matthew Geagan, CBS Boston

BOSTON (CBS) — We knew something was up with Jaylen Brown’s knee when the Celtics swingman missed two games during Boston’s five-game road trip. But Celtics president of basketball ops. Danny Ainge dropped a pretty big update Thursday morning, revealing that Brown is dealing with tendinitis.

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Deep breaths, Celtics fans. Deeeeeeeeep breaths.

It’s certainly not good news that one of Boston’s most important players is having knee problems. Brown said after returning to action Monday night in Utah that the knee has been bothering him for a while, though it didn’t look too bad as he poured in 33 points off 12-for-20 shooting in Boston’s loss to the Jazz.

Ainge attributed the ailment to Brown’s heavy workload this season, and said it’s something they’ll have to manage for the foreseeable future.

“We’re concerned,” he told 98.5 The Sports Hub’s Toucher & Rich. “But Jaylen has tendinitis in his knee, and heck, I played 14 years with tendinitis in my knee in the NBA. It comes and goes. It doesn’t mean it’s good. We’re concerned about it and are doing everything we can to lighten the load.”

Ainge said the best course of action is cutting down Brown’s minutes when they can, and giving him a day off here and there — otherwise known as “load management” in the NBA.

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“It’s a very common thing amongst NBA players. We’ll just keep tabs on it the best we can and get the best version of Jaylen that we have,” added Ainge.

Ainge just leaned about this a few weeks ago, but it’s something that has “occasionally” bothered Brown. The 24-year-old is averaging 33.3 minutes per game this season, and had played in every game before missing Friday night’s win over the Clippers.

Ainge recalls having it to deal with tendinitis early in his career when he was averaging nearly 36 minutes a game, and it went away in his 30s when his minutes decreased. Ainge will be meeting with team doctors, who were on the road with the Celtics, to discuss the best plan for Brown going forward. But it sounds like he’ll be receiving some nights off throughout the rest of the season. He sounds confident that it is something that the Celtics and Brown can manage.

“I don’t know how serious it is but I have been given no reason to be concerned about anything long term,” said Ainge. “I had it all the time and you just play with it. You usually just have to get it warmed up really good and you can function. But I don’t think there is any long term concerns at all.”

At least it sounds like Brown and the Celtics feel they can keep this from becoming a big issue. That is good news in the long term, since Brown is one of the faces of the franchise for years to come.

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But it’s an issue in the short term, as Brown has been the brightest spot in an otherwise average season for Boston. The fifth-year guard is having a career-year for the C’s, averaging a career-best 26.7 points off 52 percent shooting in his 21 games.