Kyrie Irving explains what it means to play in front of family members on Christmas, and he recognizes them as a good-luck charm. (0:39)

BOSTON -- As the Celtics trailed by two in the final 30 seconds of regulation time in Tuesday's Christmas Day thriller against the Philadelphia 76ers, they had the ball right where they wanted it: in Kyrie Irving's hands. There is, perhaps, no better shot-maker in the NBA than Irving, who has never found an angle he couldn't utilize or an arc he couldn't put on a basketball to get it to drop through the hoop.

The Sixers, meanwhile, had Jimmy Butler -- one of the league's top perimeter defenders, who himself was delivering a spectacular defensive performance -- guarding Irving for the game's most important possession. It was, in short, exactly the matchup both teams were hoping for.

Butler, true to form, was draped all over Irving, preventing him from going anywhere.

Irving kept dribbling, kept moving, trying to create enough space to get off a potential game-tying shot. Eventually, he did. And eventually -- after the ball bounced off the front of the rim and back up in the air -- it fell through the hoop with 20.9 seconds remaining, tying the game at 108 and sending it into an extra session.

"I'm about used to it now," Celtics forward Marcus Morris said. "When he first came, it was crazy. But some of the s--- don't even surprise me no more with how often he does it.

"I knew [it would go in]. I've seen it already. I've seen it a lot of times. ... It's like a replay."

Irving did it often enough Tuesday night that the Celtics emerged from the cauldron of energy that was TD Garden with a heart-stopping 121-114 victory -- a win powered by a 40-point, 10-rebound effort from Irving that, even for someone with the number of exploits he previously has had in these types of moments, had to be seen to be believed.

"That's what people, and there aren't many, in his sort of weight class do," Sixers coach Brett Brown said.

"Kyrie was elite tonight."

That certainly was true -- and a continuation of the way Irving has played all season long. And while it will be the shot-making in both the fourth quarter and overtime that will be the most celebrated aspects of Irving's outing Christmas Day, his play throughout the night only furthered the notion that this season has been the best of his career thus far.

Irving, never celebrated for his defense or his energy plays, provided plenty of both of them against Philadelphia. In one stretch alone in the first quarter, he rotated over to prevent a JJ Redick layup at the rim, outworked Sixers center Joel Embiid for a rebound and a putback layup, and drew a charge on Butler -- all while putting up 16 points in the quarter.

Those are the kinds of plays that, once a rarity, have become more commonplace for Irving this season. And as a result, it has elevated his play to a place it hasn't been before.

"I always talk about being on those big stages," Irving said. "It's just so much fun. It's competition at its highest. I love going against the best."

Still, Irving has the reputation he has as a shot-maker for a reason. And it was that shot-making that not only helped stake Boston to that early lead, but brought the Celtics home in the fourth quarter when it looked like Philadelphia had taken control of the proceedings.

Time and again, Irving managed to pull the Celtics out of the fire and back to safety:

There was the circus layup he converted after reentering the game with 8:13 remaining and the Celtics trailing by seven that jump-started a quick 10-3 run to tie the contest. There was the ridiculous shot to tie the game at the end of regulation that somehow eluded Butler's outstretched arms -- continuing a trend that, according to Second Spectrum tracking data, saw Irving go 6-for-10 and score 14 points against one of the league's best defenders. There were the back-to-back 3s midway through overtime to cap a 10-1 run that turned a five-point Boston deficit into a lead it would never relinquish. And of Boston's 20 points in crunch time, Irving scored half of them -- and hit more field goals and 3-pointers than Philadelphia's entire team while doing so.

Each of those on its own is impressive enough. But collectively, they create a performance few others in the NBA could even contemplate pulling off on any stage -- let alone on Christmas Day.

"He's done that his entire career -- take and make tough shots," said Butler, who finished with 24 points, 5 rebounds and 4 assists of his own in over 43 minutes. "That's why he is the type of player that he is in this league. That's why I respect his game so much.

"Whenever you go up against him, even [with] great defense, he can still make the shot."

Irving's heroics overshadowed so many other fascinating elements of one of the most exciting games of the season.

Philadelphia's starting lineup combined for 101 of the Sixers' 114 points, highlighting the team's ongoing depth issues.

Despite Embiid's gaudy stat line -- 34 points and 16 rebounds in 40 minutes -- Al Horford had one of the best games in which a player scored 4 points and went 2-for-10 from the field because of his efforts defensively against Embiid, whom Horford helped force into six turnovers.

It was a game that featured nine lead changes and was tied nine other times. There were multiple All-Stars on both sides, and big shots, runs and plays were made throughout.

But it was Irving who ultimately proved to be the difference, adding yet another iconic performance to a career that, despite only being halfway through its eighth season, already features plenty of them.