McCollum has collapsed lung, will be further evaluated
As a result, the eight-year pro didn't travel with the club for its matchup against the Golden State Warriors on Wednesday.
McCollum suffered the injury to his ribs on Dec. 4 against the Boston Celtics.
The team initially listed him as probable for Monday's contest against the Los Angeles Clippers before eventually ruling him out.
McCollum is averaging just 20.6 points per game this season, his lowest output since the 2014-15 campaign.