The Cleveland Cavaliers are undefeated no more. Their perfect record now has a blemish on it, at 15-1, after the defending champion Boston Celtics took them down Tuesday night at TD Garden. Jayson Tatum had an MVP moment, Al Horford continued his improbable season of hot shooting, and the Celtics logged an impressive win in front of a national audience.See omnystudio.com/listener for privacy information.