James Harden, center, and the 76ers will take on Derrick White, left, and the Celtics in the second round of the playoff starting Monday in Boston. Chris Szagola/Associated Press

BOSTON — The Boston Celtics successfully responded to the challenge an inspired Atlanta Hawks team posed over six games in the opening round of the playoffs.

The Philadelphia 76ers mostly breezed past the Brooklyn Nets in a first-round sweep but didn’t get out of it before MVP finalist Joel Embiid suffered a sprained right knee and missed the final game of the series.

Now the franchises, which have met more in the postseason than any other NBA teams, will renew their long-running rivalry in the Eastern Conference semifinals beginning Monday.

Boston has won the past five playoff series between the teams. The most recent was a sweep by the Celtic in the first round of the 2020 postseason inside the Florida bubble. This latest era of matchups has brought the history between the teams into perspective for the new generation.

“I’ve learned more about the Celtics and 76ers’ rivalry throughout time,” Boston All-Star Jaylen Brown said. “Watching Bill Russell’s Netflix series, I got to see how him and Wilt Chamberlain had a rivalry back in the day. … Bill and Wilt used to go at it, and how many people used to show up to those games and kind of how it was born.

“Just learning that history kind of gave me more foresight into today’s time.”

Brown is one of the Celtics’ stars of this current renewal, his 26.7 points-per-game average in the first round just behind fellow All-Star Jayson Tatum’s 27.2.

76ers Coach Doc Rivers said Boston’s stars are just the tip of a roster loaded with talent on both ends of the floor and experience.

“They’ve been to the Finals. They get it,” Rivers said. “They’ve been through any type of adversity. Nothing’s going to shake them and you got to be ready for that.”

One advantage Embiid and the 76ers do have, thanks to Boston’s extended series, was lots of time to recuperate after wrapping up their sweep of the Nets more than a week ago.

Embiid was spotted going through a handful of drills after Philadelphia’s practice on Sunday and was “still improving,” according to Rivers. But his status remains doubtful, Rivers told reporters. Embiid averaged 20 points and 11.3 rebounds in the three games he has played this postseason.

“We was hoping that (the layoff would) get enough time for big fella to get back and be ready for Game 1,” 76ers guard James Harden said. “But a little adversity, just to be ready to go out there and play well for Game 1, get off to a really good start and just give them four quarters of just toughness.”

Celtics Coach Joe Mazzulla said his team’s preparations haven’t changed even with the status of Embiid up in the air:

“Not so much the game plan (changes) as much as it is the understanding of who they are when he’s not in the game. That could be for 10 minutes, that could be for 48 minutes. It doesn’t matter. But they have a clear identity, and each guy is going to rise to the level of who they are when he’s not in. So we just have to be ready for that.”

SCOREBOARD

Philadelphia and Boston have met 21 times in the postseason, with the Celtics winning 14 of those series. The last time the 76ers won was the 1982 Eastern Conference finals, when Philadelphia took Game 7 in Boston.

BROWN’S FINGER

Along with Embiid’s knee, another injury to watch is a finger injury on Brown’s shooting hand.

Brown played through the first round while recovering from a cut on the webbing between his index and middle fingers. The cut split open in Boston’s Game 1 win.

“It was some ups and downs, but I managed it, I think, pretty well,” Brown said. “I ultimately just tried to help my team as much as I possibly could. But I’m feeling lot better now.”