Puerto Rico qualified for the quarter-finals of the men's basketball competition with an 87-82 win over Australia in Group B on Saturday.
Daniel Santiago scored 20 points for the victors and Elias Ayuso notched 18 as Australia sunk to their third loss.
The Aussies will struggle to reach the last eight as they face group leaders Lithuania in their final group game.
In Group A, leaders Spain progressed to the play-offs courtesy of a 76-68 defeat of Serbia and Montenegro.
World champions Serbia and Montenegro are now close to elimination and must defeat China on Monday and depend on other results to advance.
Jose Calderon scored 15 points and NBA star Pau Gasol added 14 for Spain, who have already clinched first place in their group ahead of their final game against New Zealand.
For Australia, Matthew Nielsen scored 20 points but his team could not hold on after grabbing a 51-41 half-time lead.
Carlos Arroyo, the competition's second top scorer after China's Yao Ming, gave Puerto Rico an 82-80 lead with just over two minutes remaining.
Santiago and Aussie guard C.J. Bruton traded free throws before Ayuso hit another from the line to give Puerto Rico an 85-82 edge with 28 seconds to go.
Finally, Ayuso sunk two free throws to seal victory in the dying moments.