Croatia, Serbia, Italy and the United States are the last four teams remaining in the International Swimming Federation Men's Water Polo World League Super Final.
The quartet all won their respective quarter-final matches today at the Aquatic Palace in Ruza in Russia.
Croatia were the most emphatic winners as the Rio 2016 silver medallists, who boast a 100 per cent record in the tournament, recorded a 19-3 thrashing over Kazakhstan.
Serbia are the only other unbeaten team left in the tournament.
The reigning Olympic, world and European champions defeated Japan 19-10 today.
Italy, the Rio 2016 bronze medallists, also secured a place in the final four.
They overcame Australia 13-5 in today's first match.
The US completed the semi-final line-up by beating hosts Russia this evening.
In what proved to be a tight contest, the Americans eventually prevailed 8-6.
Serbia will now take on the Americans for a place in the final while Croatia and Russia meet in the other.
The final will be played on June 25.
The Super Final is considered to be the most prestigious water polo prize outside of the Olympics and World Championships.
This year's edition of the latter will take place in Hungarian capital Budapest as part of the FINA World Aquatics Championships between July 14 and 30.