Japan routed previously unbeaten Canada 9-1 to leave the sides level on top of baseball's preliminary table.
Yoshinobu Takahashi and Kazuhiro Wada hit two-run homers and Takahashi drove in three runs to lead an 11-hit Japanese assault.
Winning pitcher Tsuyoshi Wada gave up three hits over seven innings, striking out seven and walking just one.
Cuba beat the Netherlands 9-2 to join Japan and Canada atop the table, while Australia beat Greece 11-6.
Cuba's game against Canada on Saturday now takes on extra importance with the top four teams in the eight-nation event advancing to the play-off round.
Australia stand alone in fourth, a game ahead of Taiwan and the Netherlands with two games remaining.
Earlier, Italy edged Taiwan 5-4 in a thrilling encounter courtesy of two home runs in the bottom inning.