McCollum awkwardly fell in the third quarter and was seen clutching his leg in agony. His teammates immediately helped him to the locker room, and he missed the remainder of the game.
McCollum will undergo an MRI on his knee Sunday, sources told ESPN's Adrian Wojnarowski.
The Blazers haven't needed to weather any severe injuries to their core this year, and McCollum has only missed six games since the 2015-16 season. His sophomore season is the last time he was sidelined for an extended period.
McCollum finished with 10 points, five assists, and three rebounds in 23 minutes of action Saturday.