Boston Celtics center Robert Williams III has been ruled out for the remainder of tonight's game against Charlotte after a hard spill in the second quarter. 

According to team officials, Williams suffered a lower back contusion. 

It is unclear how long Williams will be out of action with the injury. 

He joins a growing list of Celtics centers with less-than-ideal health at the moment. 

Aron Baynes remains out with a foot injury, and the Celtics opted to rest Al Horford who is suffering from some soreness in his knee. 

With the team's injury-riddled frontcourt, Williams III was making his first NBA start tonight and finished with two points, three rebounds and two blocked shots. 

The injury occurred with 1:37 to play in the second quarter and Boston trailing 60-59 when Williams III landed hard on his lower back after attempting a put-back dunk. He would lay motionless on his floor for several seconds before a time-out was called and he eventually went to the locker room for further examination. 

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