Joel Embiid scored 39 points and drained a superb game-winning jump shot with less than two seconds remaining as the Philadelphia 76ers completed a dramatic 120-119 victory over the Portland Trail Blazers on Friday.

The Sixers looked to be heading for defeat after trailing by 21 points in the second quarter, and were down by 13 with less than six minutes remaining in the final period.

But Embiid and James Harden spearheaded a late rally to haul the Sixers back into contention, shutting down the Portland offence while stitching together a run to make it a one-point game with 38 seconds remaining.

And with the clock ticking down, Embiid spun away from the Blazers' Jusuf Nurkic to drain a fadeaway jumper to put the Sixers ahead 120-119, the first time Philadelphia had led during the game.

"I knew I had to get a bucket," Embiid said afterwards of his game-winning play.

"We'd fought the whole game, come back after being down by 20 to make it a one-point game – you've got to make those plays.

"But my teammates and my coach trust me to do my job."

Embiid's 39-points came on 13-of-20 shooting and was the latest in a series of dazzling performances by the Cameroonian star.

Since the start of March, Embiid has averaged nearly 37 points a game, with tallies of 39, 39, 42, 31 and 35 over his last five appearances.

Embiid had scoring support from James Harden with 19 points, while Tyrese Maxey and De'Anthony Melton had 13 each.

Georges Niang added 12 points off the bench for the Sixers, who trailed 71-56 after a sluggish first half.

"We just couldn't get going," Sixers coach Doc Rivers said. "We looked like we were in mud in the first half, at both ends.

"That's a hell of a win for us because we didn't have a lot – and you could see it. But we just hung in there long enough, and we found a way."

It was the third time this season that the Sixers, who are third in the Eastern Conference with a 44-22 record, have come back from being down by 20 points to win.

"We don't quit, and we don't give up," Harden said afterward.

"Obviously you don't want to be down 20, but we try to find ways to stay in the game to give ourselves a chance and that's what we did tonight."

Portland meanwhile was left to reflect on a victory that slipped away at the end after a superb shooting performance from Anfernee Simons, who finished with 34 points on 13-of-22 shooting, including eight three-pointers.

Jerami Grant added 24 points and Damian Lillard had 22.

Elsewhere on Friday, the Western Conference-leading Denver Nuggets suffered a second straight defeat in a 128-120 loss to the San Antonio Spurs in Texas.

The Nuggets, who were beaten 117-96 by lowly Chicago on Wednesday, looked to have put that defeat behind them after outscoring the Spurs 38-26 in the first quarter.

But San Antonio roared back with a 42-point second quarter and outscored Denver 60-53 in the second half to seal a surprise win.

Keldon Johnson led the Spurs scorers with 23 points, with six other San Antonio players finishing in double figures.

Denver's reigning NBA Most Valuable Player Nikola Jokic recorded a 37-point triple-double – his 26th of the season.

Despite the loss, Denver remains firmly on pace for top seeding in the Western Conference playoffs, leading second-placed Sacramento by six games with a 46-21 record.

In Miami, Jimmy Butler led a fourth-quarter rally to help the Heat claim a 119-115 win over Cleveland despite a 42-point showing from the Cavaliers' Donovan Mitchell.

Miami outscored the Cavs 37-26 in the final frame, with Butler scoring 12 points as part of a 33-point display to get the Heat over the line.

Also on Friday, Brooklyn downed the Minnesota Timberwolves 124-123 in overtime while the Atlanta Hawks claimed a 114-107 road win over the Washington Wizards. (AFP)