Tetsuto Yamada homered and drove in four runs to help move Japan to within two wins of the Tokyo Olympic gold medal game with a 7-4 group stage win over Mexico on Saturday afternoon.
With their victory at Yokohama Stadium, the Japanese improved to 2-0 in Group A and booked a spot in Monday's game against the United States for a place in the semifinals.
Masato Morishita allowed two runs over five innings to earn the win. Hayato Sakamoto homered and scored twice, while catcher Takuya Kai had three hits, scored two runs and drove in one.
"Our starter Morishita surrendered the first run, but did a good job preventing runs after that," Japan manager Atsunori Inaba said. "Yamada's three-run shot gave us a boost, and Sakamoto hit one, too. Our offense was extremely efficient."
Former Orix Buffalo Joey Meneses had three hits, homered and drove in three of Mexico's runs. His first-inning RBI single opened the scoring, and his two-run eighth-inning home run off Kaima Taira kept Mexican comeback hopes alive.
Japan right-hander Ryoji Kuribayashi, however, dashed those hopes in a 1-2-3 ninth to seal the victory.
Japan tied it on three second-inning singles from Hideto Asamura, Ryosuke Kikuchi and Kai and made it 2-1 in the third, when Sakamoto doubled and scored an unearned run.
One-out singles by Munetaka Murakami and Kai set the table for Yamada's fourth-inning homer off reliever Edgar Arredondo, to make it 5-1.
Meneses' second single put runners on the corners in the home half of the fourth to set up Mexico's second run.
Sakamoto made it 6-2 in the seventh with a solo home run, and Yamada singled in another insurance run in the eighth.
Rookie right-hander Hiromi Ito pitched a 1-2-3 sixth for Japan, but pitched out of two-out two-on pickle in the seventh to preserve the four-run lead.
In Saturday's late game, Nick Martinez of Japan's SoftBank Hawks struck out nine batters over five innings to earn the win as the United States beat South Korea 4-2 to win Group B.
Mexico, which fell to 0-2, finished third in Group A, and will play Group B's last-place finisher, Israel, on Sunday in the six-team tournament's first elimination game.