Shuichi Murata smashed a two-run homer deep into the left field seats as 2006 champions Japan broke the game open with a three-run third inning at Tokyo Dome.

Chicago Cubs outfielder Kosuke Fukudome added a fourth in the sixth in a Pool A game which never really caught fire such was the gulf in class between the teams.

Japan's starting pitcher Yu Darvish struck out three without conceding a hit before being replaced after four innings of the curtain raiser for the 16-team WBC tournament.

Boston Red Sox pitcher Daisuke Matsuzaka was given the evening off ahead of Japan's next game on Saturday, expected to be against Olympic champions South Korea.

The Koreans, who won gold at last year's Beijing Games, face Taiwan in Tokyo on Friday.

The only disappointment for Japan and a crowd of 43,000 was Ichiro Suzuki's continued woes at the plate, the Seattle Mariners outfielder again going hitless.

Suzuki's average had dipped to .130 and his hitless streak stretched to 11 at-bats after Japan's final warm-up game at the weekend, before the 35-year-old went 0-5 against China.

Japan were surprise winners of the inaugural WBC three years ago but failed to win a medal at the Beijing Olympics.

South Korea beat Japan in the semi-finals before stunning Cuba to win Olympic gold. Korea and Japan are expected to advance easily to the second round of the WBC, to be held in San Diego.