They came back from bigger deficits, but the Boston Celtics mounted their most significant comeback in history against the Philadelphia 76ers, a team they’ll face in the 2023 conference semifinals beginning Monday. It was actually a double comeback.

The first part of Boston’s rally came in Game 6 of the 1981 Eastern Conference Finals. Without that, there’s no second part. The Celtics finished things off with a winner-take-all victory at home in Game 7, giving Boston an improbable berth in the 1981 NBA Finals.

The Boston Celtics rose from the dead in Game 6 of the 1981 Eastern Conference Finals

The Philadelphia 76ers made quick work of the Boston Celtics in the 1980 conference finals, winning in five games. They appeared to be on the same path in ’81, holding a 3-1 series lead heading into Game 5 in Boston.

Philly held a six-point lead with 1:51 remaining in Game 5, but the Celtics went on an 8-0 run to pull out an 111-109 victory behind Larry Bird’s 32 points. Game 6 is where the most significant comeback took place.

The series shifted back to Philadelphia, a place Boston hadn’t won in 11 straight games. Boston’s struggles in Philly were often referred to as the “Spectrum jinx.”

Philadelphia led 31-18 after one quarter. At one point, the Sixers were up by 17, and things looked grim for Boston. Led by Bird’s 25 points and 16 rebounds, the Celtics battled their way back, outscoring Philadelphia 58-47 in the second half to pull off an unthinkable 100-98 victory.

They weren’t done.

The Celtics headed back home to try and finish things off against an angry Sixers team that let the last two games get away. In Game 7, it was more of the same. The Sixers built an 11-point lead in the third quarter. They led by seven points with 5:23 left. Boston held Philadelphia without a field goal the rest of the way as the Celtics eked out a 91-90 victory, earning a berth in the championship round.

The Celtics went on to win the first of their three titles in the 1980s

Whether it was an epic collapse by Philly or not, Boston’s comeback in Game 6 was the most significant one in franchise history. Not only did it snap the Spectrum jinx, but it began an 80s dynasty in Boston.

“Everybody’s been talking about the jinx,” he said after Game 6, per Sports Illustrated. “Well, what about the law of averages? Put chimps on roller skates, let them play in the Spectrum enough times, and sooner or later they’ll win.”

Bird couldn’t understand how Philly took its foot off the gas three straight games.

“I can’t understand why Philly kept letting us back in,” Bird said.

The comeback — in Game 6 and the series — allowed the Celtics to head into the 1981 NBA Finals as significant favorites against the Houston Rockets. The Western Conference Finals featured a pair of teams — the Rockets and Kansas City Kings — with losing records. The Celtics knew there was no way they were coming up short against Houston after what they just went through with the Sixers.

“We knew we were going to win,” Celtics reserve M.L. Carr told Michael D. McClellan of Celtic Nation.  “We’d gone through such an incredible battle with the Sixers that there wasn’t a doubt in the world. 

“Beating the Rockets was a foregone conclusion. We knew there was no way we’d come up short. Talent-wise, we felt we were the superior team, and we had such a will to win after losing to the Sixers the year before and then coming back to beat them to reach the Finals. We knew we were going to take care of business.”