Their victory at the Tainan Asia-Pacific International Baseball Stadium means they are the only team left with a 100 per cent record in Group A.

Shosei Takahashi was the star performer for the Japanese as he struck a pair of two-run home runs against the side who have been runners-up at the last three editions of the tournament.

Czech Republic have moved above Chinese Taipei and into second spot in the group on the same record of two wins and a defeat.

It followed their huge 21-4 win over South Africa, in a match delayed for nearly three hours before the first inning had been completed due to a thunderstorm.

Cuba moved up to fourth by thrashing wildcard side Fiji 27-1 in a battle between two countries who were searching for their first win.

They join the South Africans on a record of won one, lost two.

In Group B, the clash between reigning champions United States and South Korea was postponed entirely due to rain and will now be held on Wednesday (July 31).

The Americans, who are aiming for a fourth title in a row, had been hoping to bounce back from their surprise defeat to Venezuela yesterday.

South Korea still top the group having won both of their matches so far, with Mexico now moving into second after beating Venezuela, who are now third, 10-6.

Both Venezuela and Mexico have played two and won one.

The US sit fourth with one win and one defeat with Italy in fifth after they beat Australia 6-4 today in a clash between two winless sides.

Group matches will continue in Tainan tomorrow.

The top three teams from each group will advance to the super round where results will carry over, with the top two teams in this then contesting the final on August 4.

All WBSC age group events count towards the organisation's overall national rankings.