OKLAHOMA CITY — Natasha Watley hit a grand slam, and Andrea Duran and Jenae Leles also homered as the U.S. routed Canada 15-0 at the World Cup of Softball today for its most lopsided victory ever against its northern rival.

Duran and Leles each hit three-run home runs as the Americans (3-0) warmed up for a rematch later in the day against Japan, which beat the U.S. 3-1 in the gold medal game at last summer's Beijing Olympics.

The Americans jumped on starter Leah MacIntosh (0-1) for five runs in the first and added nine more in the third. The game ended after four innings because of the mercy rule.

It was the fifth meeting in the last two weeks for the two countries, and the U.S. had to come from behind in two of its previous four victories against Canada.