Dallas star Kyrie Irving (32) was listed as out for the Mavericks' NBA game at Memphis on Monday with a lumbar back sprain amid reports he could be sidelined for up to two weeks.
ESPN reported Irving has a bulging disk in his back and is expected to miss one to two weeks.
"There is optimism that treatment over the coming days will provide a return-to-play target date," ESPN said, citing unnamed sources.
Irving was ruled out of Friday's loss to the Cleveland Cavaliers because of illness. He had missed a game at Sacramento the previous Monday with a sore shoulder.
The Mavs, the defending Western Conference champions, were already playing without superstar Luka Doncic, who suffered a left calf strain on Christmas Day, and have lost their last four games.
Irving, a former Rookie of the Year who won an NBA title with Cleveland in 2016, is averaging 24.3 points, 4.6 rebounds and 4.9 assists in 30 games this season.