Ben Simmons says people underestimate how hard it is to return from back surgery following his first double-double in almost 18 months in the Brooklyn Nets' 109-107 win over the Portland Trail Blazers on Thursday.

Simmons, who was traded from the Philadelphia 76ers to the Nets in February, enjoyed his best scoring game since his switch, with 15 points along with 13 rebounds and seven assists in 32 minutes.

The double-double was the Australian's first in the NBA since June 14, 2021, having not played at all last season before undergoing back surgery in May.

The much-maligned Simmons has struggled for impact upon his return to playing this season, averaging 5.8 points, 6.1 rebounds and 5.6 assists, but Thursday was a breakthrough.

"People make it seem like I had a sprained ankle or something," Simmons told reporters. "I had back surgery, that’s not easy to come back from.

"I take it day by day, I stay locked in, I stay focused and continue to build, myself, my body and my game."

Simmons has missed games this season due to injury and soreness, but he is building some momentum after making 11-of-13 from the field in his past two games, where he has posted double-digit scores.

"I'm coming," Simmons said with a grin. "I'm getting there, it's taking a little bit of time. My team-mates have got my back, my coaches."

Kevin Durant, who top scored for the Nets with 35 points, hailed the impact made by his team-mate Simmons.

"He was incredible tonight," Durant said. "I thought he did a good job of commanding the offense, commanding the team on the defensive side of the ball. He controlled the game and was able to get us back into it."

Simmons has been criticised for his free-throw shooting in the past but made three-of-four from the stripe, all coming in the final four minutes of the fourth quarter with the game up for grabs.

"We had no doubts when he walked up there," Durant said. "I felt like we all were confident, just how he was playing. I felt super confident when he went up there, so three-from-four, crunch time like that. That was key for us. We needed those.

"He shot them like he was confident. He ran back down the court like he knew they were going in. When he's playing aggressive like that, when he's downhill, he did it all for us tonight. I'm excited for him because this is the type of the game that we all needed to see.

"I think everybody else on the outside, basketball fans in general, was loving it and couldn’t wait to see this type of performance from him. We expect that from him every night."