One by one, National Basketball Association superstars are declining to participate in the FIBA Basketball World Cup from 25 August to 10 September.

Brooklyn Nets guard Ben Simmons became the latest NBA player to withdraw, saying that he can't play for Australia as he is still nursing a back injury.

The Boomers will be playing the preliminaries in Okinawa where they will face host Japan, Germany and Finland, which is fresh from an 89-85 win over Gilas Pilipinas in a friendly match in Estonia.

"Ben needs more time to focus on his rehab and he looks forward to being part of the Boomers in the future," Basketball Australia said in a social media post.

"We wish Ben all the best in his recovery."

Japan is also being bothered by personnel shortage.

Its biggest export to the NBA in Rui Hachimura also begged off as he wants to rest following a grueling campaign with the Los Angeles Lakers the past season while focusing on his options in the free agency.

"I have made the decision to withdraw from this year's FIBA World Cup," Hachimura said through the Japan Basketball Association.

"It was a very difficult decision, but after the last season stretching into the Playoffs, I decided to prioritize my future in the NBA and prepare for my first free agency."

"In addition, I will focus on working this summer to prepare for the next season."

Powerhouse Greece, France and, of course, the United States will also compete without some of their brightest stars.

The Greeks, for one, is expected to miss the services of Giannis Antetokounmpo of the Milwaukee Bucks due to leg injury while Joel Embiid of the Philadelphia 76ers and top overall pick Victor Wembanyama of the San Antonio Spurs will be skipping the French campaign.

Reports have it that Antetokounmpo is dealing with a leg injury, prompting him to skip the prestigious 32-nation tournament.