NEW YORK (AFP) — James Harden scored 45 points as the Philadelphia 76ers stunned the Boston Celtics in the National Basketball Association playoffs on Monday before Nikola Jokic and the Denver Nuggets took a commanding 2-0 series lead over the Phoenix Suns.

In a pulsating Eastern Conference duel in Boston, Harden produced a vintage performance, including a pivotal go-ahead three-pointer with 8.4 seconds remaining, to leave the TD Garden in stunned silence as the Sixers snatched a 119-115 Game 1 victory.

The Sixers' win was achieved without their best player, injured talisman Joel Embiid, who watched from the bench after failing to recover from a knee injury.

"We're just a resilient team," Harden said.

"Even without Joel, we've got the confidence to come here and win games."

"We've been doing it all year long, that's a good one for us."

Harden's points haul came from 17-of-30 shooting and included seven three-pointers.

"He was awesome," Sixers coach Doc Rivers said.

"Kept his cool, knew when to attack, knew when to give it up."

Tyrese Maxey provided offensive support with 26 points while Tobias Harris added 18 and De'Anthony Melton 17.

The Celtics were led by 39 points from Jayson Tatum while Jaylen Brown chipped in with 23 points and Malcolm Brogdon 20.

With Boston exploiting the absence of Embiid to score freely in the paint, the Celtics jumped out to lead by 12 in the second quarter.

But Harden and Maxey's scoring ensured that the Sixers remained in touch coming down the stretch with only a handful of points separating the two teams in the closing stages.

A loose pass from Brogdon with 32 seconds left on the clock handed Maxey an easy uncontested layup to put Philadelphia 114-113 up, before Tatum hit back with two free throws to give Boston a slender 115-114 advantage.