With four teams advancing from two six team groups, both sides have already made it through with two matches to spare.

The Dutch, the 2008 Olympic champions and the runners-up at the last edition of the Championships in 2014, were far too strong for Portugal as they eased to a 28-2 victory in Group A.

Lieke Klaassen, who was part of the silver medal winning team from two years ago in Budapest, scored five times in the rout with her side, who sit top, 13-2 up at the break.

Russia, in second, didn't have things quite as easy as they saw off Greece 16-6, with Anastasia Simanovich and Ekaterina Tankeeva both registering three times each.

In the other game in the group, two-time World Champions Hungary demolished Turkey 27-1 to edge closer to qualification. 

The Hungarians now boast a record of two wins and one defeat and are third, while Greece are fourth with one win and two defeats.

Both Portugal and Turkey are yet to register an opening success.

Meanwhile, the opening phase of the men's competition also continued at Belgrade's Kombank Arena with Atlanta 1996 Olympic champions Spain seeing off The Netherlands 15-4 in Group A.

In the other match in the group, Montenegro saw off Slovakia 15-6.

Croatia, the defending Olympic champions from London 2012, were far too strong for Malta in Group B as they eased to a 22-2 success.

Hosts Serbia also notched up a victory, 18-6 against France.

All 16 teams in the opening phase of the men's tournament will play in the knock-out round, with the initial matches played simply to determine who meets who.

Spain have been crowned as Group A winners and will meet Group B basement boys Malta, while Serbia topped Group B and will play Slovakia.

Montenegro, meanwhile, will play France and The Netherlands will square off with Croatia in other confirmed last 16 ties.