Ben Simmons has pulled out of the Basketball World Cup

Ben Simmons has dropped a bomb on Australia’s Basketball World Cup campaign, reportedly pulling out after an earlier commitment.

Ben Simmons is out.

Ben Simmons has reportedly pulled out of Australia’s FIBA Basketball World Cup campaign.

Simmons last month showed off on his social media accounts wearing a Boomers uniform for the first time, but he has now backflipped on his earlier commitment to playing for Australia, according to a report from ESPN’s Adrian Wojnarowski.

The report claims Philadelphia and Simmons’ agent Rich Paul have agreed that Simmons will withdraw from all international duties in order to focus only on preparations for the 76ers’ 2019-2020 NBA season.

It comes at the same time Simmons has begun negotiations on a historic new $US168 million ($A240.4 million) contract, reportedly offered by the Sixers earlier this month.

Philadelphia 76ers star Ben Simmons is "doubtful" to play for Australia in the FIBA World Cup this summer, his agent Rich Paul tells ESPN. Simmons is more likely now to spend his full offseason preparing only for the Sixers season -- free of national team responsibilities.

— Adrian Wojnarowski (@wojespn) July 13, 2019

If, as expected, the 22-year-old accepts the maximum five-year contract extension it will be the richest deal signed by an Australian athlete. ESPN reported last week the 76ers and Paul, who also represents LeBron James, “are expected to work through the details toward an eventual agreement”.

With the Boomers also hosting some of the biggest basketball contests played on Australian soil in August when they host the USA Dream Team, Simmons’ backflip is a particularly bitter blow for Aussie fans.

It also leaves Boomers coach Andrej Lemanis looking for a new star to build his team around heading into the Basketball World Cup, beginning August 31.

Lemanis has previously said his team would welcome Simmons in with arms wide open despite the fact the 22-year-old star has not made himself available for any lead-up series or training camps.

The Boomers are now left hoping American-based stars Joe Ingles, Patty Mills, Matthew Dellavedova and Aron Baynes make themselves available for the tournament.

How we all feel.

Simmons announced to the world after Philly’s loss to Toronto in the NBA Playoffs that he was coming home to play with the Boomers.

His new contract has changed everything.

“Hey guys, tough way to finish the season,” Simmons said in the video.

“I just wanted to let everybody know that we appreciate the support through the year. The home crowd was amazing, electric all season long. I’m really looking forward to getting back in the lab and putting the work in and getting ready for next season, so I’m looking forward to that.

“I’d also like to announce that I am going to be a Boomer for the upcoming events, so stay tuned.”

pic.twitter.com/Rld2p2XEEY

— Ben Simmons (@BenSimmons25) May 15, 2019

🇦🇺😤 pic.twitter.com/s7Qeph0551

— Ben Simmons (@BenSimmons25) June 19, 2019

Simmons coupled his Twitter video with a post on his Weibo account, informing his Chinese fans that he will be playing at the 2019 FIBA showpiece event, beginning August 31.

“Ni Hao China! Thanks for all the support this season, it was a tough way to go out,” Simmons wrote.

“I’m happy to say I’m looking forward to representing my country Australia in the upcoming @FIBA World Cup in China.”

Simmons was filmed earlier this week working out with Sixers star Tobias Harris, who last week signed a $180 million max extension to stay with the team.

The 76ers have had mixed success since free agency. The team was unable to retain All-Star swingman Jimmy Butler, who is joining the Miami Heat, and sharpshooter JJ Redick who moved to the New Orleans Pelicans.

But Simmons and Harris appear very committed.