The Portland Trail Blazers revealed Tuesday that guard CJ McCollum was diagnosed with a collapsed right lung, or pneumothorax, following a CT scan.
Portland said McCollum will undergo further evaluation before the team's medical personnel come to a prognosis for the 30-year-old.
McCollum sustained the injury when he fell awkwardly during the fourth quarter of the Blazers' loss to the Boston Celtics on Saturday. He was held out of the Monday game against the Los Angeles Clippers and did not make the trip with the team for a Wednesday game against the Golden State Warriors.
McCollum has spent his entire eight-plus seasons in the NBA with Portland, which made him the 10th overall pick in the 2013 NBA Draft. In 24 games this season, he has averaged 20.6 points, 4.5 assists and 4.1 rebounds.
He holds career averages of 19 points, 3.3 assists and 3.4 rebounds per game, playing his entire career in a backcourt with Damian Lillard.
Lillard is also out of commission at the moment, having been diagnosed with lower abdominal tendinopathy last week.
The Trail Blazers are 11-14.