SAN FRANCISCO -- After yet another ugly third quarter in a playoffs full of them for the Boston Celtics, it looked to all the world like the Golden State Warriors were on their way to claiming Game 1 of the NBA Finals at Chase Center on Thursday night.

But then the fourth quarter started. And, after an avalanche of Celtics 3-pointers, this game -- and series -- was completely turned on its head.

Boston hit its first seven 3-pointers to open the fourth and outscored Golden State 40-16 to stun the Warriors 120-108. In doing so, Boston became the first team in NBA Finals history to win by double-digits after entering the fourth quarter trailing by double-digits, per ESPN Stats & Information research.

"Being resilient has been the word for this year," Payton Pritchard said. "I think it showed tonight."

It certainly did in the second half. Boston has struggled the entire playoffs in the third quarter, and did again in Game 1, as it went up against a Warriors team that has historically dominated coming out of the halftime break.

The Celtics were outscored 38-24 in the third. They committed five turnovers. They let Golden State get going from 3-point range. And Jayson Tatum and Jaylen Brown combined to shoot 2-for-10 from the field.

At that point, Chase Center -- hosting its first ever NBA Finals game -- was rocking. The celebration was seemingly on. But, inside Boston's huddle, the feeling was different.

"The message at the start of the fourth was, 'We've been here before,'" Tatum said. "We know what it takes to overcome a deficit like that.

"Obviously that's a great team. It's not going to be easy. But just knowing we've been in that situation before and we've gotten our self out of it. We had a lot of time left, right? It wasn't time to hang your head or be done, it was time to figure it out."

The Celtics proceeded to do just that. It helps, of course, when a team comes out and buries its first seven 3-pointers, as Boston did. But it went beyond that. The Celtics finished the fourth quarter 9-for-12 from 3-point range.

Golden State, on the other hand, shot only 7-for-17 from the field. The Celtics stopped turning the ball over, putting up an absurd 12-to-1 assist-to-turnover ratio in the fourth. Boston's plus-24 scoring margin in the fourth quarter was the best in an NBA Finals game.

And the Celtics got contributions from up and down the roster, including Celtics coach Ime Udoka leaving the reigning Defensive Player of the Year Marcus Smart on the bench for most of the fourth quarter, opting instead to ride Pritchard for the biggest moments of Boston's season thus far.

"We pride ourselves on everybody being able to contribute on both ends," Udoka said. "That's rewarding, especially on a night when your best guy has an off night, others step up."

Derrick White continued his brilliant play since the birth of his child early in the Eastern Conference finals, scoring 21 points off the bench and hitting five 3-pointers.

Al Horford, playing in his first NBA Finals game after previously being the record holder for playoff games played without a Finals appearance, had 26 points, six rebounds and three assists, including hitting all four shots he took in the fourth quarter -- and set his career high with six 3-pointers.

Even with Tatum struggling, going 3-for-17 from the field, he still finished with 13 assists to just two turnovers, and was plus-27 in the fourth quarter without scoring a single point. He finished with four assists and no turnovers while missing all three shots he took in the quarter.

"Ecstatic," Tatum said with a smile, when asked how he felt about the game. "Forty points in the fourth quarter ... guys made big shots, timely shots as well. And we won.

"I had a bad shooting night. I just tried to impact the game in other ways. We're in the championship. We're in the Finals. All I was worried about was trying to get a win, and we did. That's all that matters at this point.

"So I don't expect to shoot that bad again. But if it means we keep winning, I'll take it."

That was the message across the board from the Celtics: That they managed to steal Game 1 while still not playing their best. Yes, they hit shots, going 21-for-41 from 3-point range. But they had that sloppy third quarter and also got off to a slow start to begin the game, when a roster that didn't feature a single player with NBA Finals experience looked like it at times in the first quarter.

"Just continue to play. That was our message throughout the whole game," Horford said. "They're such a good team. And for us, it was just, you know, continue to play no matter what.

"And our guys, that's what we did. It wasn't our best game, but we continued to fight and find different ways to get this win."

In many ways, this game was a microcosm of Boston's roller-coaster season. The Celtics were under .500 in late January, before tearing through the NBA over the final 35 games of the regular season, posting the best offensive and defensive ratings in the league over that stretch.

Boston then endured two difficult seven-game series against the Milwaukee Bucks and Miami Heat to get here, including winning elimination games on the road against both teams. They now have become the first team to beat the Warriors at Chase Center in a playoff game.

Now, after entering the NBA Finals having played 12 games in 23 days across the Eastern Conference semifinals and finals, Boston will now get another three days rest and prepare to play here again in Game 2 Sunday night, when the Celtics will have an opportunity to put a stranglehold on this series with another victory.

"It just says what we've been doing all year," Smart said. "We've been counted out all year. Rightfully so. We've had moments. But we continue to fight. That's who we are.

"I think over the last couple months, that's our identity. I think it stuck with us for a reason."

And, as a result, the Celtics are three wins away from an NBA title.