JasonTatum erupted for 51 points – the most in a Game 7 in history — and the Celtics beat the Philadelphia 76ers 112-88 on Sunday to advance to the Eastern Conference finals for the second straight year.

One game after missing 14 of his first 15 shots only to awaken in the fourth quarter in time to save their season, Tatum scored 25 in the back-and-forth first half and 17 more in Boston’s 33-10 third quarter that turned a three-point lead into a runaway.

The Celtics, who lost to the Golden State Warriors in the NBA Finals last year, will face the Miami Heat in the East finals for the second straight season. Game 1 is on Wednesday in Boston.

“I was relieved just to get another chance. Our season could have been over after Game 6,” said Tatum, who broke the Game 7 record of 50 points Stephen Curry set two weeks ago. “It definitely was on my mind that I had played as bad as it could get, for 43 minutes.

Tatum added 13 rebounds and Jaylen Brown scored 25 points for Boston, which rallied from a 3-2 deficit in the series to keep alive their hopes for an unprecedented 18th NBA championship.

“You always come into a series with the expectation of how it’s supposed to go,” said Celtics coach Joe Mazzulla, who is in his first year as an NBA head coach after being promoted on the eve of training camp after Ime Udoka was suspended. “That’s not how the playoffs are.”

Tatum was subbed out of the game with three minutes left to a standing ovation from the crowd, which soon broke out in a “Beat the Heat!” chant. Miami beat Boston in six games in the 2020 East finals and the Celtics took a seven-game matchup last season.

“It’s the best time of the year,” Tatum said. “As a competitor, I love the opportunity.”

Newly crowned NBA MVP Joel Embiid scored 15 points on 5-for-18 shooting, and Tobias Harris scored 19 for Philadelphia. The Sixers lost in the conference semifinals for the third straight year, and the fifth time in six seasons; they have not gotten any farther since reaching the NBA Finals in 2001 despite “The Process” — tanking their way to four top-three draft picks in a row, including Embiid.