Boston Celtics star Jayson Tatum had surgery Tuesday to repair a ruptured right Achilles tendon that will sideline him for the remainder of the playoffs, the team announced.

The Celtics announced the extent of Tatum’s injury and the surgery a day after the six-time All-Star went down in the Celtics’ 121-113 Game 4 loss to the New York Knicks, putting both the hopes of the defending champions repeating and Tatum’s playing status for next season in doubt.

They did not give a timetable for his return but said a full recovery was expected.

When Kevin Durant tore his Achilles tendon during the 2019 NBA Finals, he wound up missing the entire 2019-2020 season.

The 27-year-old Tatum is leading the Celtics in points (28.1), rebounds (11.5) and assists (5.4) per game for the second straight postseason.

The Knicks lead the Celtics 3-1 in their Eastern Conference semifinals series. Game 5 is in Boston on Wednesday night.

Tatum was carried off the court with 2:58 remaining in Monday night’s game. The Celtics had just turned the ball over and as Tatum moved for the loose ball, his leg gave out and he went down. He buried his face in a towel in obvious pain while grabbing at his leg above the ankle after the noncontact injury.

Tatum scored 42 points, his highest total during these playoffs and one of the best all-round postseason performances of his career, before he was hurt.

The injury was Tatum’s second this postseason. He missed Game 2 of Boston’s 4-1 first-round series win over Orlando with a bone bruise in his right wrist. It was the first time he’d missed a playoff game in his career.

Now, Tatum’s teammates will face a daunting task that few teams before them have pulled off if they want to break an NBA record six-season drought without a repeat champion.

Teams holding a 3-1 lead in the NBA playoffs have gone on to win 95.6% of the time, with only 13 teams in 293 tries ever coming back from the deficit to win the series.

“Obviously, we all realize in our heads what this could mean. This part of the sport — it’s tough,” Celtics center Kristaps Porzingis said Monday. “We have to move forward. He don’t want us to be over here sad and not play our best basketball.”

To become the 14th team to overcome a 3-1 deficit, the Celtics will need big performances from a roster that has several players who have dealt with injuries this postseason.

Trail Blazers go up for sale: Paul Allen’s estate announced Tuesday that it has begun the process of selling the Portland Trail Blazers.

The sale of the team is “consistent with Allen’s directive to eventually sell his sports holdings and direct all estate proceeds to philanthropy,” the Trail Blazers said in a statement.

Allen, the billionaire co-founder of Microsoft, died in 2018 at age 65 from complications of non-Hodgkin’s lymphoma.

Allen was also owner of the Seattle Seahawks and co-owner of Major League Soccer’s Seattle Sounders.

He bought the Trail Blazers in 1988, telling the The Associated Press at the time that “for a true fan of the game, this is a dream come true.”