The United States remained undefeated in Tokyo Games softball on Monday, defeating defending champion Japan 2-1 in a rematch of their 2018 world championship final and a preview of Tuesday's gold medal game.

Winners of the first three softball Olympic golds before Japan upset them in the 2008 Beijing Olympic final, the American women came from behind in the sixth inning at Yokohama Baseball Stadium and walked off on Kelsey Stewart's leadoff homer in the seventh off Yamato Fujita.

Yamato Fujita of Japan pitches against the United States in the opening round of the Tokyo Olympic softball tournament on July 26, 2021, at Yokohama baseball stadium near Tokyo. (Kyodo)

"It was fun playing America after such a long time," said Fujita after going the distance in a game that was essentially a dead rubber with both teams having already qualified for the final.

"There was nothing on the line, so I just wanted to execute my pitches. They have a lineup filled with power hitters so I tried to keep them on the ground."

That plan worked with Japan's infield playing in close against the Americans' speed and making some outstanding defensive plays as Fujita did not allow a hit through five innings. The U.S. had two one-out scratch singles in the sixth to set up Valerie Alioto's two-out game-tying RBI single.

A day after surrendering their first run of the tournament to Australia, the Americans fell behind 1-0 in the first to a prototypical Japan-style small-ball attack. A misplayed hot shot off Saki Yamazaki's bat led to an error and a runner on first with no outs. A sacrifice bunt, a Hitomi Kawabata single and a passed ball put Japan ahead.

Ally Carda, who plays in Japan's women's league for Honda, started for the United States. She allowed an unearned run while striking out nine over 5-1/3 innings. Lefty Monica Abbott, who plays in Japan for Toyota, worked a 1-2-3 seventh for the United States to earn the win.

It was the first big game between the teams since the United States came from behind to beat Japan in a thriller to win the 2018 world championship in Japan.

"You want to win every game you play," Japan manager Reika Utsugi said. "And we always want to beat the U.S. I thought we could hit them a little better because their pitchers play in Japan."