Celtics' Robert Williams in for Game 7, but how much will he play?

Robert Williams

BOSTON -- Robert Williams is (mostly) back.

The Celtics' starting center is available to play in Game 7 of the Eastern Conference semifinals against the Milwaukee Bucks on Sunday, head coach Ime Udoka confirmed.

Williams won't start, however, and will only play on an "if needed" basis, per Udoka.

"He hasn't done a whole lot of basketball activity in the past week," Udoka said of Williams. "Just more so just managing the pain, and structurally he's OK.

"We'll go with our normal rotation the last three games with him being out and use him if needed. ... We're not relying on him to come back for Game 7 to save the day.

Williams missed the previous three games of this series in part due to a left knee bone bruise he suffered in Game 3 after a collision with Bucks star Giannis Antetokounmpo.

That collision exacerbated the soreness Williams has felt since returning from left meniscus surgery on April 23. He's averaging 5.3 points, 4.8 rebounds and 1.5 blocks over five games played in the postseason to date.

Still, the Celtics will take Williams' minutes wherever they can get them. Milwaukee dominated Boston on the offensive boards in Game 5 (17 to five), and Williams can help in the rebound department when he's on the floor while providing more frontcourt depth alongside Al Horford, Grant Williams and Daniel Theis.

NBC Sports Boston's coverage of Celtics-Bucks Game 7 begins Sunday at 2:30 p.m. ET with "Celtics Pregame Live" ahead of 3:30 p.m. ET tipoff.