BOSTON (CBS) — Celtics big man Robert Williams was once again listed as questionable for Boston’s must-win Game 6 in Milwaukee on Friday night. And Robert Williams was once again ruled out just prior to game time.

Celtics head coach Ime Udoka made the announcement during his pre-game press conference in Milwaukee.

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“[He’s] disappointed as we all are, but looking out for health first and foremost,” said Udoka. “The pain is still there and we’re not going to put him out there until he’s 100 percent.”

He added that the pain has been limiting Williams’ movement in practice, so the Celtics aren’t taking any chances with the 24-year-old center.

Williams was a late scratch for Game 4 and was listed as questionable ahead of Game 5, and ultimately missed his second straight game Wednesday night with swelling in his left knee. He underwent surgery on that knee in late March after tearing his meniscus and missed about a month of action.

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Earlier Friday, Udoka revealed that it’s actually a bone bruise that has caused the soreness.

“He got his knee scanned and everything structurally is good. The swelling went down, but he still has some soreness,” said Udoka. “He has a bone bruise that he suffered in Game 3 so that’s where the soreness is from.”

Udoka said the bone bruise occurred on a play where Giannis Antetokounmpo ran into Williams.

Williams started the first three games against Milwaukee, playing 23, 25 and 22 minutes, respectively. He averaged 8.7 points, 5.7 rebounds and 2.7 blocks over those three contests, but was not his usual bouncy self and appeared tentative at times on the floor.

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With Williams out, the Celtics will likely turn to their other Williams — Grant Williams — in the starting five for Game 6. The Celtics are down 3-2 in their playoff series against the Bucks, but a win on Friday would force a Game 7 in Boston on Sunday afternoon. Staff