Updated

Portland, OR (SportsNetwork.com) - An MRI Thursday confirmed a low back contusion that will keep Portland Trail Blazers All-Star forward LaMarcus Aldridge out at least two games.

Aldridge left Wednesday's loss to the Spurs in the third quarter after colliding with San Antonio center Aron Baynes. He was helped to the locker room and did not return.

Portland will need its star big man healthy for the postseason push. Aldridge has enjoyed a breakout season, averaging career-highs with 23.4 points and 11.1 rebounds per contest.

He is expected to sit the next two games and will be re-evaluated later in the week.

The Blazers will also be without reserve guard Mo Williams, who has a right hip strain. Williams is expected to miss about two weeks.