The Celtics have a slim 1 1/2 -game lead over Cleveland for the eighth playoff spot in the Eastern Conference. Boston trails New York by a half game for seventh.
Portland is in a three-way fight with Denver and Utah for the final playoff spot in the Western Conference. The Trail Blazers trail the Jazz by a half game for eighth place in the West.
Portland would lose tiebreakers to Denver and Utah if it finishes tied with either team.
The Blazers are in the middle of a stretch of four straight games against teams in the thick of the Eastern Conference playoff race. A three-game road trip began in New York and continues in Boston and Philadelphia before the Blazers return home to play New Orleans on Saturday.
Damon Stoudamire missed an off-balance 20-footer at the buzzer as Portland began the trip with a 92-91 loss to the Knicks at Madison Square Garden on Monday.
Stoudamire had 20 points and Zach Randolph 19 for the Blazers.
“This one hurts,” coach Maurice Cheeks said. “It always helps to get the first one because it gives you momentum to get the second one.”
Boston has won three straight and five of the last seven.
“The team is really coming together at an important time of the year,” Pierce said. “We’re making our run for the playoffs.
STANDINGS (through March 29): Trail Blazers - 3rd place, 15 GB, Pacific Division. Celtics - 4th place, 8 1/2 GB, Atlantic Division.
TEAM LEADERS: Trail Blazers - Randolph, 20.2 ppg and 10.6 rpg; Stoudamire, 6.2 apg. Celtics - Pierce, 22.9 ppg and 5 apg; Blount, 7 rpg.
SEASON SERIES: Trail Blazers, 1-0.
LAST MEETING: Feb. 21; Trail Blazers, 105-84. At Portland, the Trail Blazers jumped out to a 22-0 lead behind Randolph’s 27 points and 15 rebounds. Chris Mihm had 15 points to lead the Celtics.
ROAD/HOME RECORDS: Trail Blazers - 13-23 on the road; Celtics - 17-20 at home.