Jaylen Brown had an MRI scan on his hamstring on Sunday and is listed as doubtful for their Eastern Conference semifinal opener against the Philadelphia 76ers.
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Coach Brad Stevens said Brown "still has some soreness" in his hamstring, however the results of the MRI "looked good" and he could still play early in the series.
Brown has picked up the slack in terms of scoring since Kyle Irving was ruled out for the postseason with a knee injury, averaging 20.5 points across the first six matches against the Bucks.
But the 21-year-old hobbled out of game seven, revealing after the 112-96 win that he is set for tests on the issue ahead of the Celtics' next game on Monday.
"It's a little sore. It could be worse," Brown said. "Get an MRI [on Sunday] and see how it feels and go from there.
"I just did a move and it just popped a little bit, pulled it a little bit, but it'll be all right."
CELTICS IN 7 #CUsRise pic.twitter.com/S7IG7Z9rZJ- Boston Celtics (@celtics) April 29, 2018
He added that he will do "whatever it takes" to be fit, saying: "I wouldn't miss this next series for the world."
This is just the latest blow for the Celtics, who have also been without Gordon Hayward for all but two minutes of the season, although Marcus Smart is now back from his thumb injury.