Walker, who was listed as questionable by the Boston Celtics, didn't participate in shootaround and underwent an MRI on his knee after telling the team Friday night that he had knee soreness, according to Celtics coach Brad Stevens.
"Kemba got ahold of our doctors last night and said he had some knee soreness," Stevens said. "[He] went and got an MRI today, [and it] didn't show anything structurally wrong, but he's very sore."
Walker, who played in all 82 games last season and missed a combined six games over the prior three seasons, has already missed five games this season for the Celtics: three for a recent bout with the flu, another after hurting his neck in a game against the Denver Nuggets in November and then Saturday's game because of his knee.
He spent the game sitting on the bench next to Jaylen Brown, who sat out for a second consecutive game with a right thumb sprain. Stevens said he was hopeful Walker's would not be a long-term absence.
"I haven't talked to him enough to know," Stevens said. "Once they ruled him out for tonight, had to think about how to get ready for tonight. I'm always concerned when someone's not feeling right, but I don't get the impression it's a long-term thing."
Walker, 29, is averaging 22.1 points and 4.9 assists in 36 games for the Celtics, and is expected to make his fourth straight All-Star team later this month. Boston entered Saturday night's game in its worst stretch of the season, having lost five of its prior seven contests.