Boston Celtics center Robert Williams III (44) drives to the basket against Milwaukee Bucks center Brook Lopez (11) and center Bobby Portis, right, during the second half of Game 2 of an Eastern Conference semifinal in the NBA basketball playoffsTuesday, May 3, 2022, in Boston. Credit: Charles Krupa / AP

BOSTON — The Celtics will officially miss Robert Williams III for the second straight game because of left knee soreness, Boston coach Ime Udoka said pregame. Udoka said they’re being “extra cautious” with Williams, though the swelling is down.

Williams was originally listed as questionable on Tuesday’s injury report ahead of Game 5, which is set for 7 p.m. Wednesday at TD Garden. But Williams was downgraded to out. Williams was an unexpected late scratch ahead of Game 4 because of his knee, which forced the Celtics to adjust.

Grant Williams was inserted into the starting lineup in place of Rob Williams, and Udoka said Grant Williams will start again Wednesday. While Grant Williams had been excelling in the series, he struggled in Game 4 and played only 24 minutes while going 1-for-5 from 3-point land.

The Celtics also had to adjust on the fly because of foul trouble. They were already down one big man in Williams. Udoka also leaned on Daniel Theis for spot minutes, but Theis only struggled in his limited time as he also went 0-for-5 from the field. Udoka said Theis will again see more minutes Wednesday.

Williams suffered a torn meniscus in the March 27 win over Minnesota, which required surgery. The original timeline for Williams’ return was 4-to-6 weeks. Williams was a few days ahead of schedule when he came back for Game 3 against the Nets on April 23. Williams got a small ramp-up in the first-round series against the Nets, where he combined to play 30 minutes in Games 3 and 4.

After the week off between the Nets and Bucks series, Williams was expected to be a full go as he returned to the starting lineup in Game 1 vs. Milwaukee. However, Williams hasn’t quite looked like himself in recent games as his minutes were down and he hasn’t had the same impact on both ends of the court.

Story by Souichi Terada,