Montenegro could face Serbia in the water polo final after beating Croatia
World champions Croatia crashed out to Montenegro in the quarter-finals of the men's Olympic water polo competition.
The Croats had been strongly fancied to claim gold but the 7-6 defeat by the European champions saw them eliminated.
Montenegro will face defending champions Hungary in Friday's semi-finals, while Serbia will take on the United States.
Serbia and Montenegro played as one country at the last Olympics, but could now face each other in the final.
In 2004 they nearly beat Hungary in the gold medal match, but the country split in 2006 and the national team was split between the two nations.
Both semi-finals will be rematches from the group stages where Serbia won a defensive battle against the United States, 4-2, and Hungary and Montenegro drew 10-10.