BOSTON — Jayson Tatum and the Celtics had higher hopes for Christmas Day’s matchup against the Philadelphia 76ers at TD Garden.

The motivation of a well overdue response to Monday night’s crumbling to the undermanned Orlando Magic, coupled with the spirit of the holiday season, however, just wasn’t enough. Boston swallowed a tough pill in the form of a 118-114 loss to Philadelphia despite Jayson Tatum’s (loud) return to the floor — Tatum recorded a 32-point, 15-rebound double-double and shot 11-of-20 from the field.

Admittedly, it wasn’t an overall team effort up to par for the reigning NBA champions.

“There’s things that we gotta address. We gotta be better,” Tatum said postgame. “It’s still a long season. Nobody’s panicking. You just have to be able to navigate the emotional rollercoaster of an NBA season. It feels a lot worse than it actually is. We’re not panicking or anything. We gotta man up and look in the mirror and figure out some things that we gotta do better at. Everyone’s fully capable and we’ve always done a good job at responding and I have no doubt that we will.”

Oddly enough, the Celtics did respond to their defensive underperformance — by holding the Sixers to 16 points in the third quarter — but the momentum was short-lived.

Boston’s sign of life in overcoming 60 points combined between Tyrese Maxey and Joel Embiid, plus Caleb Martin’s seven 3-pointers made, quickly took an untimely U-turn and sent the Celtics back to square one. There, Boston sat scratching its head and watched a 108-105 deficit in the last 2:25 minutes of regulation turn into an outpouring of fans fleeing for the exits.

“I think we gotta take some ownership,” Tatum confessed. “We gotta be better. We gotta acknowledge the things that we’ve done not so great. We gotta look in the mirror and man up, and we just gotta be better. We fully believe in ourselves, the things that we can do when we’re fully locked in and we’ve done it time and time again. We’ve just had some lapses recently. We just gotta get back on track.”

The Celtics committed 13 turnovers to Philadelphia’s six, shot 61.5% from the free-throw line (on 13 attempts) and never held a lead in the double figures. It didn’t just rain, it poured, leaving Boston in the same place it entered the floor on Christmas Day — in need of a refueling response to light a fuse.

And even though the Magic — without Paolo Banchero and Franz Wager — and the Sixers — who are still climbing out of the Eastern Conference’s coffin at 11-17 — got the better of Boston, the Celtics aren’t questioning who they are deep down.

“I feel like being to three straight conference finals, two Finals appearances in the last three years, we’ve been getting everybody’s best shot over the last three years,” Tatum said. “So it’s not something that should catch us off guard or anything like that. It should be something that’s expected.”