Terry Rozier added 16 points for the Celtics, who outscored Portland 38-23 in the fourth quarter.
Damian Lillard and CJ McCollum each scored 26 points for the Trail Blazers, who lost their second straight game following a 13-game win streak. Al-Farouq Aminu collected 16 points and 10 rebounds for Portland.
Aminu had 11 points and six rebounds and Lillard 10 points and five assists to propel Portland to a 52-47 lead at halftime. Morris scored 14 points for Boston.
The Blazers increased the difference to 65-53 on a McCollum drive and dunk. Portland's advantage was 77-67 heading into the fourth quarter.
The Celtics opened the final period on a 15-6 run to close to within 83-82. Morris buried a three to give Boston an 85-84 lead with 6:31 to play. McCollum scored on a drive to push Portland back ahead 86-85. Rozier sank a pair at the line to give Boston an 87-86 advantage with 5:25 left.
McCollum's three-point play pulled the Blazers into an 89-87 lead with 5:05 to go. When McCollum followed with a left-handed floater, Portland's edge was 91-87 with 4:39 remaining.
Al Horford drilled a trey to get the Celtics to within 91-90 with 4:23 to play. Horford then split a pair at the line to tie it at 91-91 with 3:48 left.
Lillard buried a 3-point shot to give Portland a 94-91 lead with 3:12 to play. Morris answered with a 3-pointer for Boston, and Rozier sank two free throws to give the Celtics a 96-94 lead with 2:13 remaining.
Lillard's left-handed finish off a drive tied it at 96 with 1:50 to go, but Jayson Tatum pushed Boston ahead 98-96 on a drive with 1:29 left. When Morris drilled another three, the Celtics' advantage was 101-96 with 54.8 seconds remaining.
Lillard hit two foul shots to close the gap to 101-98 with 47.9 seconds left. Tatum and McCollum traded baskets, and Boston milked the clock to inside 10 seconds. Tatum missed a jumper but Horford rebounded. Rozier's two free throws with 3.2 ticks left iced it for the Celtics.
Boston got out to a 10-5 lead. Portland answered with a 13-2 run to go ahead 18-12. The Blazers settled for a 26-23 advantage going into the second quarter.
Portland increased the margin to 33-25. A four-point play and a 17-foot jumper by Morris drew the Celtics to within 40-38. A Morris layup tied it at 42, but Portland came away with a five-point bulge at the half.
--Field Level Media
Boston | Portland | |
Marcus Morris 30 | Scoring | Damian Lillard 26 |
Shane Larkin 7 | Assists | Damian Lillard 8 |
Greg Monroe 10 | Rebounds | Al-Farouq Aminu 10 |
Marcus Morris 7 | Free Throws Made | Damian Lillard 4 |
Jayson Tatum 2 | Steals | Al-Farouq Aminu 5 |
Al Horford 2 | Blocks | Al-Farouq Aminu 1 |
Team | Points | FG% | 3PM-3PA | FTM-FTA | Assists | Rebounds | Blocks | Steals | Turnovers |
Boston | 105 | 45.5 | 11-18 | 24-26 | 22 | 45 | 4 | 5 | 13 |
Portland | 100 | 44.0 | 8-33 | 12-15 | 16 | 43 | 5 | 8 | 8 |