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Boston Celtics center Robert Williams III underwent surgery Wednesday morning to repair the torn meniscus in his left knee, and is expected to return in approximately four-to-six weeks, the team announced. The timetable sets Williams up for a potential return in the second round of the playoffs. 

Williams suffered the injury in a win over the Minnesota Timberwolves on Sunday, and further imaging revealed the torn meniscus. He had become a key part of the NBA's best defense during Boston's recent surge. The Celtics have won 24 of their past 29 and sit just one loss behind the Miami Heat for first place in the Eastern Conference.  

Their top-ranked defense, giving up 105.9 points per 100 possessions and only 103.4 since Jan. 22, has been at the center of that revival. Williams is perhaps the best player on that defense. His athleticism and length playing largely as an off-ball rover has made him one of the most dangerous defensive playmakers in basketball. Boston has relied on the Williams-Al Horford tandem to protect the rim for them, but with Williams now out, the onus will fall on the rest of Boston's defense to help carry the load.

The Celtics fortunately do not lack elite defenders. Horford is having an excellent season. Marcus Smart will likely earn All-Defense honors. Jayson Tatum, Jaylen Brown and Derrick white have all shined as well. But Boston's defense had been perhaps the most dangerous overall weapon any team in the NBA had over the past few months and it just took a serious hit.

Williams has ascended so quickly that he has actually played more minutes this season (1,804) than he had in his entire career beforehand (1,656). He is averaging career highs in points (10), rebounds (9.6), blocks (2.2), assists (2.0) and steals (0.9). He has started every game he has played this season, typically in tandem with Horford. Now Boston will have to decide how it wants to rearrange its lineup with Williams sidelined.

The Celtics could try to use Daniel Theis in two-big lineups as it has Williams, but his athletic limitations will make it hard for him to match the impact Williams has had. Grant Williams is another option, but like Theis, he lacks Williams' nuclear athleticism. Playing White and going smaller with just one big man (Horford) is another option, and it would probably provide a bit of extra offensive punch as well. Ultimately, though, there is no ideal answer. Williams was essential to the Celtics, and his recovery will be a key to Boston potentially making a run to the Finals.