Celtics rookie Daniel Theis is likely out for the rest of the season with a torn meniscus in his left knee.
Theis underwent further testing Monday morning after suffering the injury in Sunday's home loss to Indiana.
Theis, a 25-year-old rookie from Germany, had become a key contributor off the bench for the Celtics, averaging 5.3 points and 4.3 rebounds this season.
Coach Brad Stevens told reporters Monday (Tuesday, Manila time) that the center is weighing his surgical options. Kyrie Irving (knee), Jaylen Brown (concussion), Marcus Smart (thumb), Shane Larkin (knee) and Al Horford (illness) are all dealing with their own issues.
Boston (46-21) now has a firm grip on the second seed in the Eastern Conference, but lost Theis, Marcus Smart and All-Star guard Kyrie Irving to injuries in Sunday's loss to Indiana.
The bulk of minutes that Theis spent against bigger, plodding opponents will presumably be allotted to Greg Monroe, but the Celtics have also recalled Guerschon Yabusele from the G-League to provide additional frontcourt depth.