- Jayson Tatum (left knee contusion) and Al Horford (low back stiffness) both missed the Celtics‘ double overtime loss to Cleveland on Monday. As Tim Bontemps of ESPN observes (via Twitter), Horford played 45 minutes on Sunday and still hasn’t played both ends of a back-to-back set this season, so his absence came as no surprise. Tatum sustained his injury in a collision on Sunday.