Washington Wizards swingman Sheldon Mac suffered a serious injury to his lower left leg Sunday night in the team’s exhibition game against the Cleveland Cavaliers. The Wizards fear that Mac tore his left Achilles’ tendon, according to a source. He is scheduled to have an MRI on Monday. In the second quarter, Mac attempted to drive from outside the right arc. As Mac planted his right foot, it appeared as if his left leg could not complete the move. Mac grimaced in pain and then crumpled to the floor. Teammates surrounded Mac before he was carried off the court by two trainers with 4:34 remaining in the quarter.