Ray Allen scored 17, and Kendrick Perkins had 11 points and a season-high 12 rebounds to go with a career-high six assists. Point guard Rajon Rondo had six points and eight assists one day before the Celtics are expected to bring in backup Sam Cassell, who was waived last week by the Los Angeles Clippers.
Josh Smith scored 20 points and added nine rebounds, and Al Horford had 14 and 11 for the Hawks, who missed a chance to move into a tie for the eighth and final playoff spot in the Eastern Conference. Newly acquired Mike Bibby had 14 points and nine assists.
The Hawks led 46-41 after Bibby’s alley-oop to Horford for the first basket of the second half. But Boston scored the next 13 points — including nine in a row from Pierce — before Smith hit a free throw with 8:42 left in the quarter.
Pierce added a jumper that gave him 11 consecutive Boston points and gave the Celtics a 58-47 lead. Atlanta came within three points several times, the last at 73-70, before Eddie House hit a 3-pointer with 9:05 to play.
Notes:@ P.J. Brown did not dress for the Celtics. … Cassell was bought out by the Clippers on Friday and is expected to clear waivers at 6 p.m. Monday. … The Celtics play the Detroit Pistons on Wednesday in a matchup of the top two teams in the East.