South Sudan defeated Great Britain 84-81 at London’s Copper Box Arena as they prepare for their first Olympic Games in Paris.
Unlike Royal Ivey’s side, GB did not qualify for the Paris Olympics and failed to bounce back from recent defeats against Portugal and Argentina.
South Sudan narrowly led the end-to-end encounter 44-42 at half-time and the game remained tight throughout.
Marial Shayok was the visitors’ top scorer with 27 points, followed by 15 points from Bul Kuol.
The game went down to the last play as South Sudan successfully defended GB’s final attack to deny a three-point throw to tie the game.
It was a special day for South Sudan Basketball Federation president Luol Deng, who returned to London, having played there for Great Britain at the 2012 Olympic Games.
The second game of this Summer Series at the Copper Box Arena takes place on Sunday at 15:00 BST when the Great Britain women’s team play Germany.
South Sudan will next face the United States at the O2 Arena on 20 July as they continue their Olympic preparations.
Basketball at the Paris Olympics will run from 27 July-11 August.
There are two medal events – men’s and women’s – with the men’s final taking place on 10 August and the women’s on 11 August.