Durant injured the ankle Thursday in a loss at Golden State. He sat out the Thunder's win at the Los Angeles Lakers the next night and a loss to New Orleans on Sunday.
Thunder coach Scott Brooks says Durant remains day-to-day. Oklahoma City will play at San Antonio in a Christmas Day game.
Durant missed the Thunder's first 17 games because of a fracture in his right foot. The 2014 NBA most valuable player is averaging 22.4 points, 5.0 rebounds and 3.6 assists in nine games this season.
Portland also will be without at least two players and maybe three. Robin Lopez has a fractured right hand and Nicholas Batum has a sprained right wrist. All-Star forward LaMarcus Aldridge has an upper respiratory illness and is questionable.