Shohei Ohtani helped Samurai Japan script a perfect ending to a perfect first round at the World Baseball Classic.

Ohtani hit a three-run home run in the top of the first inning, Yoshinobu Yamamoto dominated on the mound and Japan defeated Australia 7-1 in front of a crowd of 41,664 at Tokyo Dome to complete a perfect four-game romp through Pool B at the WBC on Sunday.

"It was a valuable first run," Ohtani said. "I was eager to hit one."