Australian basketball superstar Ben Simmons is unlikely to play in the Tokyo Olympics after a terrible performance in the NBA finals.

Simmons, 24, had his NBA season finish in devastating fashion, with the Philadelphia 76ers stunned by underdogs Atlanta in their Eastern Conference semi-final series.

The point guard also didn't feature in the 2016 Olympics in Brazil or the 2019 Basketball World Cup.

Simmons' expected absence in Japan is a significant blow to the Boomers' medal chances as it tries to upset basketball powerhouses.

ESPN's Brian Windhorst tweeted Simmons chose to focus on 'working on skill development' in his NBA offseason rather than represent his country in Japan.

Free-throw shooting is a key area Simmons needs to improve in his game, he said.

Simmons is contracted to Philadelphia to the end of the 2024-25 NBA season, but may consider options elsewhere after the 76ers were bundled out of the finals and he copped a deluge of blame for the loss.

He won't be short of suitors, with San Antonio, Portland, Washington, Houston, and Toronto all said to be watching on with interest.

A fresh start in the NBA could be the tonic Simmons needs to revitalise his career.

He has been widely criticised for his ineptitude at the foul line and his fear of driving to the basket in the shock finals loss.

His poor free-throw shooting proved fatal for the Sixers, who were expected to easily beat the Hawks.

Simmons shot a woeful 25-for-73 from the line in the playoffs and missed 27 alone against Atlanta.

NBA legend Shaquille O'Neill was brutal in his assessment of Simmons.

'If I played Game 1 and 2 and I know I’m not helping my teammates, what do you think I’m going to do in Game 3?' the Basketball Hall of Famer fumed, according to The New York Post.

'It doesn't take seven games for you to know that you're not playing right, get right.

'He (Simmons) didn't get double-teamed, just be aggressive, that's all I want.

'I don't want to hear all that, stop that. If he was in my locker room I would have knocked his ass out. I don't want to hear that, get out of my face with that.'

Sixers coach Doc Rivers is confident Simmons can rectify the deficiencies in his game.

'There's work (to be done). And Ben will be willing to do it,' he said. 'Sometimes you have to go through stuff to see it.'

Australia open their Olympic campaign on July 25 at the Saitama Super Arena in Tokyo when they take on Nigeria in a Group B clash