Kevin Garnett had 13 points, 13 rebounds and thousands of fans who turned out to cheer for the former face of the Timberwolves franchise. The Celtics led by 25 early in the second quarter, but trailed by two midway through the fourth before Pierce lifted them to the victory.
Michael Beasley had 28 points and 10 rebounds for the Timberwolves, who were missing All-Star Kevin Love for the third straight game because of a strained left groin.
Anthony Tolliver's 3-pointer gave Minnesota an improbable 73-72 lead with just over 5 minutes to play, but Pierce came back with a 3-pointer and drive to take back the lead.
The Celtics played without starting point guard Rajon Rondo, who strained his right pinky finger in practice on Saturday. Delonte West filled in well with eight points and five assists to help Boston avoid its first three-game losing streak of the season.
Darko Milicic had 15 points and nine rebounds, and Tolliver added 16 points and 15 boards for the Wolves, who trailed 38-13 in the second.
Coach Doc Rivers lit into his veteran unit after the Celtics gave away a 13-point lead in a home loss to Charlotte on Friday night, calling them selfish pouters who are feeling sorry for themselves. It was an eye-opening assessment of a team that appeared to be hitting a wall with the postseason just a few weeks away.
Six losses in 10 games allowed the surging Bulls to jump into the top spot in the East, and the Celtics started the day 2 1/2 games behind Chicago in the conference.
Rivers' blistering appeared to wake the Celtics up early. Playing the kind of hard-nosed defense that has been their calling card for the Garnett years, they ripped off a 23-3 run in the first period to jump out to a huge lead.
Without Love in the lineup, the Wolves missed 22 of their first 27 shots and were getting pounded on the boards. Anthony Randolph, who had averaged 27.5 points and 13 rebounds in his two previous starts in Love's place, played just 3 1/2 minutes in the first half because of foul trouble.
Boston also scored the first six points of the second quarter for a 38-13 lead — much to the delight of scores of fans wearing Celtic green — and the nose-diving Wolves looked to be well on their way to another uncompetitive night at Target Center.
But the Wolves gradually started chipping away at the lead as the first half closed, cutting the deficit to 13 points at the break. Milicic's hustle on the offensive glass jump-started them midway through the third period, starting a 22-6 run that tied the game at 62 just before the fourth quarter.
Milicic's layup with just over 8 minutes to play gave Minnesota its first lead of the game, 70-68, and the Wolves all of a sudden were outshooting the Celtics after their putrid start.
But after Pierce stabilized the Celtics, Garnett added two big jumpers, and forced a turnover by Milicic, and the Celtics breathed a huge sigh of relief.
Timberwolves backup C Nikola Pekovic missed the game with a hip injury. … A Wolves win would have tied the largest comeback in franchise history. They beat the Charlotte Hornets after trailing by 25 points on March 1, 1996. … Nenad Krstic had 11 points and six boards for Boston. … Rivers said he was unsure if Rondo would be able to play at Indiana on Monday night.