Getty Images

Boston Celtics starting center Robert Williams III is available to play in Game 4 of the Eastern Conference finals against the Miami Heat on Monday night, the team announced ahead of tipoff. Williams missed Game 3 as he's dealing with persistent soreness in his left knee. Boston, however, won't have guard Marcus Smart, who's dealing with a sprained ankle he suffered in Saturday's loss. 

Toward the end of March, Williams underwent surgery to repair a torn meniscus in his left knee and did not return until Game 3 of the team's first-round series against the Brooklyn Nets. His return lasted only five games, however, as he suffered a bone bruise in the same knee during Game 3 of the team's second-round series versus the Milwaukee Bucks

Williams missed the final four games against the Bucks, but was finally cleared to play again for the Eastern Conference finals, and suited up for the first two games in Miami. It's not clear if something happened during Game 2, or if Williams is dealing with continued pain from the previous injuries. 

In any case, missing him in Game 3 proved to be detrimental as the Celtics lost 109-103 to fall behind 2-1 in the series. Getting him back for Game 4 will provide Boston with a boost in the frontcourt, and while Williams doesn't always put up big numbers, he's the best rim protector on the team and blocked five shots in the first two games of this series. Opponents cannot attack the basket in the same way when he's healthy. On the other end, Williams is a big-time lob threat who gives the Celtics a vertical option around the basket, and an effective offensive rebounder. 

As for Smart, he already missed Game 1 of this series with a mid-foot sprain. The Celtics sorely missed his defensive presence and playmaking as it dropped to opening game of the Eastern Conference finals. He injured his ankle in the second half of Game 3, but managed to return shortly after exiting. Celtics coach Ime Udoka said ahead of tipoff that Smart's ankle was still "quite swollen." They'll have to lean on guards in Derrick White and Payton Pritchard in Smart's absence.