Latvia stunned defending champions Spain as the Basketball World Cup second round got under way on Friday, while the United States, Lithuania, Germany and Slovenia booked their places in the quarter-finals.

Italy, Brazil and Puerto Rico shook things up with upset wins over previously unbeaten Serbia, Canada and the Dominican Republic.

Tournament debutants Latvia pulled off an almighty shock when they beat Tokyo Olympic silver-medallists France in the group stage.

They added world and European champions Spain to their giant-killing conquests after scrapping to a 74-69 win in Jakarta.

Latvia head coach Luca Banchi said his team arrived at the tournament in the Philippines, Indonesia and Japan desperate to "prove that we belong at this level".

"Being an underdog in such a tough group, and suffering so many injuries before arriving and during the competition, for sure put us in a position where we don't have anything to lose," he said.

"We arrive here with real desire to prove our style, good or bad. Without any credit, it makes an extra strength."

Latvia looked to be heading for defeat when Spain took a 58-47 lead into the fourth quarter but they outscored the previously unbeaten defending champions 27-11 in the final period.

Power forward Davis Bertans led Latvia in scoring with 16 points but he said the team's performance was all that counted.

"I really don't care about any of the numbers on the stat sheet," he said.

"I know that every single guy gives 100 percent and more, every time they step out on the court."

Elsewhere in Group L, Brazil beat previously unbeaten Canada 69-65 to leave all four teams on three wins going into the final day's play.

Olympic revenge 

Slovenia advanced to the quarter-finals with a 91-80 win over Australia that eliminated the Boomers from title contention.