Olympic champions Serbia began their World League defence with victory ©Getty Images

Defending champions Serbia eased to victory as the International Swimming Federation (FINA) Water Polo World League began today with the first qualifying matches across Europe.

The Serbians, who won the men's water polo tournament at the Rio 2016 Olympics in August, brushed aside Romania 19-8 in Group A on home territory in Kragujevac.

Three European groups are being contested in all, on a home and away basis.

Only the trio of group winners will make it through to the next year's Super Final, which has yet to be allocated a host nation or dates.

In the other match in Group A, Slovakia beat visitors Germany 10-7 in Košice.

London 2012 champions Croatia beat Greece ©Getty Images
London 2012 champions Croatia beat Greece ©Getty Images

Group B saw Croatia, the London 2012 gold medallists who were second behind Serbia in Rio, claim an 11-6 home win over Greece in Rijeka.

The other match in the group saw The Netherlands edge visitors France 11-10 in Gouda.

In Group C, a three-team group, the sole match contested saw the only away win of the day as Russia pipped Georgia 14-13 in Tbilisi.

The qualifiers for the Super Final will be joined by the host nation, as well as four non-European teams who progress from an Intercontinental Tournament.

Serbia won the 2016 Super Final in Huizhou in China by beating the United States 10-6 in the final.

The second round of European qualifiers will be played on December 6.