Brooklyn Nets head coach Steve Nash remains optimistic that Ben Simmons will play at some point this season but has revealed the new signing has a herniated disk in his back.

Simmons is yet to debut for the Nets following his February trade from the Philadelphia 76ers, whom he fell out with over the off-season. The Australian guard has subsequently not played all season.

The former All-Star had an epidural last week to alleviate pressure in his back as he struggles to build his conditioning up to a level fit enough to see him return to action.

The Nets, who appear headed for the Play-In Tournament with a 37-34 record sitting eighth in the east, have only 11 regular-season games remaining, meaning the clock is ticking on Simmons.

"He's had this [herniated disks] a couple years ago, so he's had them throughout his career at some points," Nash told reporters prior to Sunday's game against the Utah Jazz.

"I guess there was a flare-up. I'm not sure when they recognised it was beyond a back flare-up and a herniated disc or what not, but somewhere along the line there, that was the reason for the epidural."

He added: "From what I know, he trained pretty hard for five, six months. He was in a great place. Unfortunately, I think there was a little flare-up at some point in there and it's just never quite turned the corner since.

"I think he had months of five, six days a week on court and was doing very well, so just unfortunate, but we stay the course. Hopefully a good resolution to this in the near future."

Simmons is yet to be cleared to return to practice although Nash said surgery had not yet been discussed.

"We still have high hopes that he can come back," Nash said. "He's had moments during his rehab where he's on the court doing some things and it looks like he's about to turn a corner, and then there's a little setback so I still feel optimistic that he can play for us."