Basketball’s World Cup launches on Saturday in China with two-time defending champions the United States missing their biggest stars and looking uncharacteristically vulnerable after surrendering their long winning streak.

The chief threat to the LeBron James-deprived Americans looks likely to come from Serbia, but Spain, France, Australia and Greece – led by NBA MVP Giannis Antetokounmpo – are all snapping at Team USA’s heels.

A total of 32 countries will begin in eight groups of four spread across cities in China, from Shenzhen in the south to the capital Beijing, where the final will be held on September 15.

Just a few days ago the United States under their respected coach Gregg Popovich were odds-on favourites to make the final and win it for the third time in a row, no matter the opponent.

But last weekend they were stunned 98-94 by Australia in Melbourne, the hosts ending the USA’s run of 78 consecutive wins in major competitions and exhibition games.

Then followed another setback with Los Angeles Lakers forward Kyle Kuzma ruled out of the World Cup with an ankle injury.

San Antonio Spurs mastermind Popovich has been forced to name a young squad after numerous high-profile NBA stars opted out including James, Kawhi Leonard, Stephen Curry, James Harden, Anthony Davis, Russell Westbrook and Paul George.

Kevin Durant, Kyle Lowry and Klay Thompson are injured.

The Americans bounced back in Australia to beat Canada 84-68 in their last warm-up match before jetting over to China, but their aura of invincibility has dimmed and the players have admitted that they are still getting to know each other.

Myles Turner, a centre with the Indiana Pacers, said that his team-mates needed to adapt fast to the international game.

“A lot of times in the NBA you sort of wait until the fourth quarter to turn it on,” said Turner.

“You have to turn it on from the jump here.

“And these teams, everybody wants to beat the USA. We’re the top dog and everybody’s gunning for us night in and night out.”

The US begin their title defence in Shanghai on Sunday when they play the Czech Republic in Group E, which also contains Japan and Turkey, runners-up to the Americans in 2010.

Serbian warning

If anyone is going to finally dethrone the US, many fancy it could be Serbia, beaten by the US in the final in 2014. The US also defeated the Serbs in the final at the 2016 Rio Olympics.

But unlike their title rivals, Serbia will be able to call upon most of their big names from the NBA, including All-Star Nikola Jokic.

The 24-year-old Denver Nuggets man, touted by some as the best centre in the sport, has what it takes to be the player of the tournament.

Coach Aleksandar Djordjevic warned his side, who will play the first match of the tournament, against Angola, not to be “exhibitionist”.

“They should play simply, together, very responsibly,” Djordjevic told local media, calling for “strong discipline at every moment”.

While much of the interest in China will focus on the Americans and the fight for their crown, it is not all about the title.

Final placings in the tournament are critical because seven teams will qualify directly for next year’s Tokyo Olympics and the rest can advance their 2020 Games dreams.

As hosts there will be added pressure on China, who lack a successor to trailblazer Yao Ming but still look likely to qualify from Group A, which also includes Ivory Coast, Poland and Venezuela.

If that pool is comparatively weak, Group H – comprising Canada, Australia, Senegal and Lithuania – has been dubbed the “Group of Death”.

Canada are led by Nick Nurse, the 52-year-old American coach who had barely finished celebrating the Toronto Raptors’ first NBA title when he agreed to take on the Canada job two months ago.

The World Cup sees 92 matches take place over 16 intense days of action.