LAKE BUENA VISTA, Fla. -- As the Boston Celtics have rebuilt their team into an Eastern Conference contender the past few years, they have done so around the idea that Jayson Tatum and Jaylen Brown will be franchise cornerstone players for years to come.

Monday night, Tatum and Brown showed how that vision is beginning to come together. Tatum's 32 points and 13 rebounds and Brown's 29 points -- including 15 in the fourth quarter -- propelled Boston to a 109-101 victory over the Philadelphia 76ers in Game 1 of their first-round playoff series inside the NBA bubble at the Walt Disney World Resort.

"We've just got to fight," Brown said afterward. "That's what it comes down to. Who wants it the most? Who wants to fight?

"Today, we came out and we battled. We were the more physical team and we came out on top. I was proud of us. We've got to keep that fight up if we want to win this series."

The Celtics needed every bit of Tatum's and Brown's exploits to survive against the 76ers, who got 26 points and 16 rebounds from Joel Embiid, but were forced into 18 turnovers -- that became 21 Celtics points -- as Boston used its speed and athleticism defensively to make up for its lack of size against the much bigger Sixers.

Brown also relentlessly attacked former teammate Al Horford down the stretch, including a key moment when Boston took the lead for good with a 6-0 run powered by Brown blowing by Horford, causing him to wrap up Brown for a level one flagrant foul. Brown made both free throws, then drove by Tobias Harris to earn another two free throws, which he made.

When Philadelphia chose to stick with Horford in its starting lineup -- as opposed to starting rookie Matisse Thybulle -- it chose to try to use its size to punish Boston, and hoped it would be able to take advantage of Brown guarding him. Instead, it was the other way around, with Brown either shaking free for 3-pointers -- he shot 5-for-8 from deep -- or using his speed to snake through the defense for layups.

"Al's a terrific defender," Celtics coach Brad Stevens said. "And I think that we're just doing our best to try to get a good look every time down the court. We'll keep looking at what we can do to play better offense."

A good place to start is to give the ball to his two young wings and get out of the way. Tatum scored 21 points in the first half -- a playoff career high -- and finished with three blocks en route to a game-high plus-19 in 41 minutes.

Although Ben Simmons did a terrific job shutting down Tatum when the teams met during the regular season, holding him to just a 28% effective field goal percentage in those matchups -- the second-worst mark of any player against a defender who guarded them for more than 30 shots, per Second Spectrum's tracking data -- his absence was a significant problem for the Sixers, as Tatum had no trouble getting to his spots.

It was especially noteworthy late in the game when he was isolated against Josh Richardson on the wing and drove to the rim and easily drew a foul, knocking down two free throws to extend Boston's lead to five with 41.4 seconds remaining.

"Yeah, he was really good," Stevens said. "I thought he was unbelievable defensively the whole game, talking and helping, and communicating and reading, and he just makes a bunch of -- he makes a huge impact on that end. Then, offensively, it doesn't feel like he got 32 at the end of the night.

"He just plays the game within himself and finds the next right play. He did a lot of good things tonight."

The Celtics will need more of that from their young wings if Gordon Hayward, who exited the game late in the fourth quarter with a right ankle sprain, is out for significant time. They still have to deal with the size mismatch inside against Embiid, who dominated early before Boston was able to swarm Philadelphia's ball handlers and prevent him from getting the ball -- as well as rushing him and taking the ball when he tried to post up.

But Brown and Tatum have been here before. While both are on rookie contracts -- Brown is in his fourth season and Tatum his third -- both have won at least one playoff series each year they've been in the league, and both have been to the Eastern Conference finals. That experience was evident as they closed out the Sixers.

"Experience is everything," Brown said. "That's the best teacher. I've been lucky enough to be to two Eastern Conference finals, so I feel like I bring a lot of experience. [Tatum] also has been to a conference finals, so continue to feed that to our young guys and play like you've been here before."

They did that Monday. And after his first playoff game alongside them, point guard Kemba Walker saw everything he has seen from his young running mates in his first season in Boston carry over to the playoffs.

"It's special," Walker said. "Those two dudes are super special talents. They showed it today. Every big moment, they made big plays. Whenever we needed a big play, they made it.

"It's just fun to watch. It's really fun to be a part of their growth."