Nikola Jokic scored 29 points and unheralded bench player Julian Strawther produced a crucial late burst as the Denver Nuggets clinched a series-leveling 119-107 victory over the top-seeded Oklahoma City Thunder on Thursday.

A hard-fought NBA Western Conference semi-final series will now go to a decisive game seven in Oklahoma City on Sunday after another ferocious duel between two evenly matched teams.

Serbian star Jokic was once again the anchor of a composed Denver performance, finishing with 29 points, 14 rebounds, and eight assists to shepherd the Nuggets to victory.

Jamal Murray added 25 points while Christian Braun finished with 23. But arguably the most significant contribution came from the bench, with Strawther scoring 15 points.

"Tonight we had a guy step up," Nuggets interim head coach David Adelman said of Strawther's performance. "He made some shots and then our main people were still complementary."

Denver's win came after they had fallen 3-2 down in the series following late stumbles to lose games four and five.

"Those losses were tough but the series is still here," Adelman said. "I know it's a cliche, but every game is its own chapter, its own thing, its own entity, and different people are going to step up.

"And now we've put ourselves in a position where we can say, 'Hey, let's go see what happens on Sunday'. And I know I've got a group of guys that have been in a lot of game sevens and seen a lot of things. So we're excited for the opportunity."

Oklahoma City looked ready to clinch a series victory after surging into a 12-point lead late in the second quarter at Denver's Ball Arena.

But Denver, as they have done all series, once again refused to roll over and rallied to trim the Thunder lead to 61-58 at the break.

There was little to choose between the teams for most of the third quarter, and with just under two minutes remaining in the frame, the score was level at 80-80.

Yet within moments, Denver had suddenly opened up a double-digit advantage after a 10-0 run that put the Nuggets into a 90-80 lead.

The scoring spree came from an unlikely source, with the 23-year-old Strawther, in only his second season in the league, suddenly finding his scoring range.

Strawther knocked down back-to-back three-pointers, followed by a layup to rattle in eight of the 10 points in the Denver run.

With their noses in front, the 2023 NBA champions ruthlessly held a firm grip on the contest through the fourth quarter, keeping the Thunder safely at arm's length to close out the win.

Shai Gilgeous-Alexander led Oklahoma City's scoring with 32 points while Chet Holmgren finished with 19.

Oklahoma City coach Mark Daigneault said his team, which recorded a league-best 68 wins in the regular season, would be ready to bounce back on its home court on Sunday.

"First of all credit Denver -- they threw a punch tonight, as has happened all series," Daigneault said. "Both teams have been exchanging blows and they got theirs in tonight.

"Both teams have done a great job so far of getting back up, including us, and we need to do that on Sunday.

"Other than that, we need to be who we've been all season and embrace the opportunity that's in front of us.

"We get to play that game at home on Sunday because of the work we did during the regular season. So we're obviously disappointed in the outcome tonight, but when the ball goes up in the air we'll be excited to go."