BOSTON — The Celtics appeared to be skipping toward the second round of the NBA playoffs following a 32-point road win in Game 4 at Philadelphia.

But Boston has suffered back-to-back losses to the 76ers and a team that once looked like a favorite to emerge from the Eastern Conference is on the brink of an epic collapse.

If the Celtics loses Game 7 on Saturday it would be their earliest exit from the playoffs since the 2020-21 season.

It won’t have that star Jayson Tatum is dealing with a new ailment after he briefly left Game 6 in the third quarter for treatment on an apparent left calf injury. Tatum, of course, is just 22 games into his return from the torn right Achilles tendon injury he suffered in last season’s playoffs.

The Celtics downplayed the situation. Tatum said afterward that his leg was only feeling “a little stiff.” He said following a quick assessment and some time on the exercise bike he didn’t return because the game was out of hand and the starters had already been pulled.

Coach Joe Mazzulla said there was no injury at all and reiterated that in a conference call Friday.

“He’ll play,” Mazzulla said.

The recent history for winner-takes-all games for Philadelphia teams isn’t exactly on the 76ers side, though. The Flyers are the last Philadelphia team to win a Game 7, beating the Bruins in the 2010 Eastern Conference semifinals.

Since then, the 76ers in 2012, 2019, 2021 and 2023 have all lost Game 7s; the Flyers lost one in 2014 and 2020; and the Phillies lost Game 7 of the NLCS in 2023.

The Phillies also lost a decisive Game 5 in the 2011 playoffs.

The Celtics have long had the Sixers’ number in the playoffs, winning the last six series. The 76ers last eliminated the Celtics in the 1982 Eastern Conference semis.

“I’ve been playing these guys for so long,” 76ers star Joel Embiid said. “I’m tired of losing to them. We have a chance to accomplish something special.”