The Boston Celtics handed LeBron James and the Los Angeles Lakers their worst defeat of the NBA season on Monday, routing the Western Conference leaders 107-139. Jayson Tatum scored 27 points, and Kemba Walker returned from injury to add 20 for the Celtics, who snapped a three-game skid with the upset triumph. Enes Kanter came off the bench to score 18 points and pull down 11 rebounds for the Celtics, who had lost six of their past eight games.