Two-time defending champion Japan beat China 5-2 on Sunday in Fukoka, Japan, to improve to 2-0 in Group A of the World Baseball Classic.
With Japan up 2-0 in the bottom of the fifth at Fukuoka Dome, Yoshio Itoi broke the game open with a bases-clearing double to centre field that made it 5-0 for the hosts.
Japan starter Kenta Maeda picked up the win after striking out six and giving up one hit over five scoreless innings.
"Our pitchers did very well tonight," Japan manager Koji Yamamoto said. "We've been a little worried about Maeda coming in but he went out tonight and pitched a very strong game, which will give us confidence."
Japan would have had a more comfortable win had it not been for a shaky outing by reliever Tetsuya Yamaguchi who surrendered China's first run on a wild pitch in the ninth and allowed another on a fielder's choice before recording the final out.
China got two of its three hits in the top of the ninth when it put pressure on Japan for the first time.
"Baseball is new in China and this was just another step," China manager John McLaren said. "I thought the guys played really hard. We didn't hit much until the end of the game so we're just trying to get better with every game."
Japan took a 1-0 lead in the bottom of the second when Sho Tanaka singled to left scoring Itoi from second. Seiichi Uchikawa made it 2-0 in the fourth on a single to right before Itoi's clutch double.
Cuba beat Brazil 5-2 earlier Sunday in its first game of the tournament. Brazil dropped to 0-2.
Two teams from the group will advance to the March 8-12 second round at Tokyo Dome with a chance to move on to the March 17-19 championship round in San Francisco.
Japan next faces Cuba on Wednesday.