The Bucks said Monday night Parker would not return.
Parker's knee appeared to buckle on a drive to the basket before he collided with the Suns' P.J. Tucker, and Parker was unable to get to his feet immediately afterward.
Parker, the Bucks' first-round draft pick this year and the second player chosen overall, had to be carried off the court by teammates to the locker room.
Parker had eight points in 15 minutes. He's averaging 12.5 points and 5.6 rebounds per game.