LOS ANGELES — In their comeback season, the Celtics saved the biggest one of all for the NBA finals.

Boston rallied from a 24-point deficit and beat the Los Angeles Lakers 97-91 on Thursday night to take a commanding 3-1 lead in this history-rich series and move within one victory of a 17th championship that seemed impossible a year ago.

A rivalry between the league’s two most storied franchises — with some of the game’s biggest names and biggest moments — now has its biggest rally.

No team had ever overcome more than a 15-point deficit in the first quarter, and although the league doesn’t have a record for the largest rally in a finals game, the Celtics staged one that will forever be remembered in the annals of Celtics-Lakers lore.

When the final horn sounded, Paul Pierce, an L.A. kid playing in front of family and friends, doubled over in exhaustion and exuberance. The Celtics, the team he stuck with through 10 years, including a 24-win season in 2006-07, had done the impossible.

“We sucked it up,” Pierce said. “We said we weren’t going to back down.

“At the end of the third quarter I looked up at the scoreboard and told the fellas, ‘We just have to go out there and compete and let the chips fall where they may.'”

Pierce scored 20 points, Kevin Garnett had 16 points and 11 rebounds and Ray Allen had 19 points as Boston’s Big Three, thrown together last summer by general manager Danny Ainge to revive a franchise accustomed to hanging banners from the rafters, put the Lakers on the brink of a summer vacation.

It took an epic comeback to do it, and now the Celtics can reclaim their place atop pro basketball with a win in Game 5 on Sunday night in Los Angeles.

No team has ever recovered from a 3-1 deficit in the finals.

“It can always happen. We aren’t counting on that statistic,” Pierce said. “We want to take care of this on Father’s Day.”