Rozier fires Celtics as Boston down Sixers
Horford finished with 26 points while Tatum added 28 points as Boston surged into a 1-0 lead in the best-of-seven series with a statement victory.
The third-seeded Sixers had advanced to the semi-finals after a confident demolition of Miami in the opening round.
J.J. Redick had 20 points for the Sixers, while point guard Ben Simmons had 18 points from 41 minutes on the court.
Boston, who advanced to the semi-finals after a gruelling seven-game series win over Milwaukee, have regrouped superbly after a slew of injuries which means they are without stars Kyrie Irving, Jaylen Brown and Gordon Hayward.
Rozier’s 29-point haul included 21 points from three-point range, a 77.8 conversion percentage from outside the arc.
Game two takes place in Boston on May 3.