Brooklyn Nets head coach Steve Nash believes the referees are to learn how to officiate the NBA's new rules on taking fouls after James Harden had 20 free-throws in Friday's 115-113 win over the Orlando Magic.

Harden starred in the absence of Kevin Durant for the Nets with 36 points including 19 from the line.

The 2018 NBA MVP's form has been down to start the season, with his inability to draw fouls under the new rules seen as partly responsible.

Harden only had 15 free-throws in his first five games this season, but has drawn 43 in the Nets' past three games.

Nash said the uplift in the numbers was a combination of Harden being more aggressive and the referees officiating differently.

"I think both. I think the referees are starting to figure out what's still a foul and what's not a basketball play," Nash said at the post-game news conference.

"I think early it was difficult for them to know what the line was. He's such a difficult guy to over with his size, quickness and ability to shoot over anyone from three.

"Guys have to get too close to him, he's so strong once he gets a slight angle on you or step on you, it's almost impossible not to foul him.

"That's what makes him brilliant, his ability to penetrate and take contact."

Nash was full of praise for Harden, who has scored 35 or more points in two of the Nets' past five games as begins to re-discover his top form.

Harden is averaging 20.3 points, 7.6 rebounds and 8.8 assists per game this season, but he is also averaging 28.4 points from his past five games.

"Great competitiveness, playing for the team, spirit was great," Nash said. "Obviously he can do some playmaking out there. He can attack the basket with his quickness and size.

"He rebounded the ball for us. Huge effort for him everyone pitched in. It was not an easy game for us. we had to find a way to make it happen."

Durant missed the game with a shoulder sprain but Nash said it was not a major concern.

"We don't feel concerned that it'll linger or that he'd miss the next game," he said pre-game.