Mongolia moved to the top of Pool B as the only side to secure two wins on the opening day, including a tense 14-12 victory over Russia.

They followed this up with a 20-17 victory over Estonia to top the pool despite having only the fourth-best points average of the five teams.

Second-ranked Russia, Ukraine and Puerto Rico picked up one win and one loss, meaning there is everything to play for when the pool resumes on Thursday (June 20).

In Pool D, Poland are the surprise leaders after beating fourth-ranked Latvia 15-13 in the final match of the day at Museumplein.

Poland, ranked 14th in the competition, are the only side in the pool with a perfect record after two games, having edged out Australia 18-16 earlier.

Australia, Latvia and fifth-ranked Japan each have one win, while Brazil suffered defeats in both their games.

In the women's competition, top seeds China made a strong start with victories in their two opening Pool A fixtures.

They hammered Turkmenistan 22-5 before a more testing game against Latvia, which they eventually won 18-12.

Ninth-ranked Hungary are also well positioned after beating Latvia 15-9 and winning a tight contest against the Netherlands 13-11.

It means China and Hungary occupy the two Pool A qualifying slots, with the Chinese ahead on points average, 20 to the Hungarians' 14.

Romania and Spain earlier took control of Pool C with wins from both of their opening matches.

Having watched the first three pool games play out, Romania stepped up with back-to-back victories, beginning with an eye-catching 22-4 victory over second-ranked Mongolia, before defeating Czech Republic 21-13.

Spain have both Mongolia and fourth-ranked Romania still to play, but a 22-8 win over Iran to kick off the tournament, followed by a 21-14 victory over the Czechs, gives them a shot at qualification.

Mongolia, despite being the top-ranked side in Pool C, sit bottom with a points average of 11.

They need a major turnaround on Thursday (June 20) in order to qualify.