Sure, the Sixers are young. But so are the Celtics. And when things get tight like they did Saturday night — when the opponents are hitting miracle shots and taking four-point leads in overtime — the kids turn to veteran Al Horford.

And they're not alone.

"He's the stabilizer for our group. There's no question about it," Celtics coach Brad Stevens said after Boston's stunning 101-98 overtime win. "When things go poorly, everybody just kind of looks to Al, including the coaches."

Rookie Jayson Tatum led the Celtics with 24 points. Terry Rozier, who is seeing his first extensive playing time in the playoffs, had 18. Ditto for Jaylen Brown, who had 16 points. Those were the high scorers.

But it was Horford, scoreless in the first half, who made the difference at the end of overtime. He scored seven of Boston's 12 points in the extra session.

"Al is our leader. He's been in the playoffs every year [except one], so he's been in every situation possible," said Tatum, who gave the Sixers fits all night by making 11-of-17 shots. "He's always making sure we're in the right situations. We know we can look toward him to make the right play at the end of the game."

With 5.5 seconds left in overtime and the Celtics down one, Horford took an inbounds pass, sealed off Robert Covington, who fruitlessly tried to defend, and hit the shot that put Boston up one.

Then Horford made a steal on a bad inbounds pass by Ben Simmons and sank the ensuing free throws when Joel Embiid was forced to foul. More about that in a minute.

"I'm always just trying to stay in the moment as much as I can, and I want the guys to focus and enjoy these moments," said Horford, who has the Celtics on the verge of a sweep and his third career trip to the Eastern Conference finals. He's never gotten beyond them. "These are the kind of moments you want to be in as a basketball player. We just stayed with it. Kept fighting. I just felt like we made a lot of winning plays down the stretch."

It was so physical out there, it often resembled a hockey game. Embiid managed 22 points and 19 rebounds despite some sticky defense often from Horford and Aron Baynes.

Baynes had the unfortunate luck to be on the poster end of a monster Embiid jam in the second quarter that shook the Wells Fargo Center crowd. Embiid took 26 shots on the night, 25 in the paint and fouled out on that Horford steal at the end of the game.

It was not lost on Embiid that Horford, who had 13 points in 42 minutes, was not whistled for a single foul all night.

"It was physical. [Boston] did a good job," Embiid said. "But I don't see how it's possible for someone to guard me and have zero fouls. I thought a couple of plays weren't fair. You have to give Al a lot of credit. He competed. He made some plays for his team, and he got them the win.

"But, like I said, I'm too big. I mean, I guess it's the playoffs. It's my first time here. I'm learning. But I'm too big not to be fouled every time I go to the basket or every time I post up."

Hmmm. Sounds like Horford's an equal opportunity educator.