Olympic gold and bronze medallists Serbia and Italy both booked their place in the Super Final of the International Swimming Federation (FINA) Men's Water Polo World League with a game to spare.
Both countries claimed victories in the latest round of European qualifiers to ensure they cannot be caught at the top of their groups.
Serbia, who beat Croatia in the final of the Rio 2016 Olympic tournament in August, hammered Germany 20-3 in home water in Zrenjanin.
It ensures they will top Group A with a game to spare, with only the winners progressing to the Super Final in Moscow between June 20 and 25.
The Serbians are hoping to win the World League for the fifth straight year, while they are also the reigning world and European champions.
Slovakia beat visitors Romania 6-5 in Group A's other game in Kosice.
Italy ensured they won the three-team Group C as they beat guests Russia in Palermo 12-9.
They cannot be caught, but the Russians will play in the Super Final anyway as the host nation.
Group B remains up for grabs with one round of matches to go.
Olympic silver medallists Croatia and Greece both won today and are locked on 12 points each at the top.
Croatia, who lead the way with a superior goal difference of plus 29 compared to Greece's plus 16, eased to a home 16-6 win over France in Vukovar.
The Greeks made the trip to The Netherlands and came away with a 10-4 win in The Hague.
France will entertain Greece with Croatia welcoming the Dutch for the final round of qualifiers on April 11.
As well as the three group winners and Russia, four qualifiers from the Intercontinental Water Polo Tournament will also contest the Super Final.
Australia will host the event in Gold Coast between April 25 and 30, welcoming Japan, China, Kazakhstan, New Zealand and the United States for a round-robin competition.