Japan beat Puerto Rico 4-2 in their WBSC Women's Baseball World Cup opener ©Getty Images

World number-one ranked side Japan started their World Baseball Softball Confederation (WBSC) Women's Baseball World Cup defence with a comeback victory against Puerto Rico in Miyoshi.

Group B of the WBSC Women's Baseball World Cup began today at the Miyoshi Kinsai Stadium, with the top two teams in the six-side round-robin set to advance to next year's Finals in Thunder Bay in Canada.

Japan's First Lady Yuko Kishida threw the ceremonial first pitch before their first match, but watched her team fall 2-0 behind to world number nine-ranked Puerto Rico in the third inning.

However, runs provided by Yuki Kawabata, Miwa Naraoka, Akari Hoshikawa and Tamaki Muramatsu in the fourth ensured Japan won the match 4-2.

"It was really an intense game," Japan's manager Risa Nakashima said.

"I will discuss details with the players tomorrow before our pre game practice, but I'm happy we took off with such an intense game."

In the first match of Group B, world number-two ranked side Chinese Taipei fell behind to Cuba but recovered to start with a 9-1 victory.

France started their match against Venezuela with their first-ever run at a Women's Baseball World Cup from Angélique André.

However, Venezuela replied strongly with an 11-1 triumph in six innings.

The second round of Group B matches is scheduled for tomorrow with Chinese Taipei facing Venezuela, Cuba playing Puerto Rico and Japan taking on France.

Teams are set to face each other once with matches taking place until Sunday (September 17).