The Portland Trail Blazers have revealed CJ McCollum suffered a collapsed right clunk in a defeat to the Boston Celtics last weekend.
McCollum was injured in the final quarter of an emphatic 145-117 loss at the hands of the Celtics on Saturday.
The guard missed a 102-90 defeat to the Los Angeles Clippers on Monday and a scan revealed the extent of the damage done.
Portland stated that McCollum, who is averaging 20.5 points, 4.1 rebounds and 4.5 assists this season, will be out indefinitely.
The 30-year-old joins All-Star Damian Lillard (abdominal injury), Anfernee Simons and Nassir Little (both ankle) on the sidelines.
Portland also lost guard Ben McLemore to a hip injury during the defeat to the Clippers, while center Cody Zeller is struggling with a bruised right quad.