SAN FRANCISCO, United States (AFP) — Al Horford led an electrifying fourth quarter comeback as the Boston Celtics stunned the Golden State Warriors 120-108 to draw first blood in their best-of-seven NBA Finals series on Thursday.

Celtics veteran Horford scored 26 points, including 11 in the fourth quarter, as Boston inflicted Golden State’s first home defeat of the post-season at their Chase Center fortress.

Horford’s tally included what turned out to be a decisive burst of eight unanswered points in the fourth quarter as the Celtics pulled clear having trailed by 12 at the end of the third period.

Boston defensive linch pin Marcus Smart also came up big late on with back-to-back three pointers as the Celtics surged into a double-digit lead against a shellshocked Warriors.

The victory was no less than Boston’s gutsy never-say-die approach deserved in a full-blooded contest that resembled a heavyweight title fight, full of wild momentum shifts, twists and turns.

“Just continue to play. That was our message throughout the whole game,” Horford said afterwards.

“They’re such a good team. And for us, it was just, you know, continue to play no matter what. That’s what we did.

“It wasn’t our best game, but we continued to fight and find different ways to get this win.”

Boston twice recovered from double-digit deficits either side of halftime when it looked as if the Warriors were poised to cut loose.

Not even a dazzling shooting display by the Warriors’ Stephen Curry — who exploded for 21 points in the first quarter alone including a record six three-pointers — could fluster the Celtics.

Despite a vastly less experienced line up — not a single player on the Boston roster had played an NBA Finals game before Thursday — the Celtics refused to crack under pressure.

Instead it was the Warriors whose resistance crumbled in a fourth quarter that saw the home side outscored by an astonishing margin of 40-16.

“That’s kind of who we’ve been all year,” Celtics coach Ime Udoka said.

“Tough grinders, resilient group that we can always know we can rely on our defense to kind of buckle down when needed.”

Boston’s win was all the more notable as it came with only a modest contribution from star Jayson Tatum, who finished with 12 points and 13 rebounds.

“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.

“So it is rewarding, and knowing we can play so much better, that’s the main thing. Didn’t have a great three quarters and kept ourselves in the game, then locked down when we needed to.”

Golden State coach Steve Kerr paid tribute to Boston’s fourth quarter display.

“Those guys, give them credit,” Kerr said.

“My gut reaction, what I just witnessed, they came in and played a hell of a fourth quarter, and you have to give them credit. It’s pretty much as simple as that.”

– Blow-for-blow –

Horford led a balanced Boston offensive effort that saw five players finish in double figures.

Jaylen Brown finished with 24 points with seven rebounds and five assists while Derrick White added 21 points. Smart added 18 points.

Curry led the Warriors scorers with 34 points while Andrew Wiggins finished with 20 and Klay Thompson 15.

Otto Porter Jr. had 12 off the bench, but the Warriors were left ruing their catastrophic fourth quarter when they made just seven of 17 from the field.

No one could have foreseen the Celtics’ fourth quarter onslaught during a third quarter when it appeared that the Warriors’ greater experience was finally beginning to tell.

The Warriors had pulled into what looked like a game-winning position after outscoring the Celtics 38-24 in the third to open up a 12-point lead.

It had been a similar story in the first half, when Curry’s first quarter performance left Boston scrambling to compose themselves.

Yet despite Curry’s brilliance, Boston were always in touch, with their dogged defense and balanced offense restricting the Warriors lead to just four points at 32-28 at the end of the first quarter.

The Warriors threatened to pull away in the second, surging into their biggest lead of the half to go 10 points clear at 47-37.

But once again the resilient Celtics responded brilliantly, rattling off a 10-0 run to draw level at 47 points apiece with just over five minutes remaining in the half.

After the feast of scoring in the first quarter, Curry endured a famine in the second, scoring zero points as the Celtics eventually edged clear to lead 56-54 at the break.

The Warriors have the chance to level the series in game two in San Francisco on Sunday.

© Agence France-Presse