Crystl Bustos hit a home run as the Americans won 11-0
The US women's softball team set a new Olympic record with an 11-0 rout of Venezuela in their opening game.
Natasha Watley hit a two-run homer as the match was halted after five innings under the run-rule.
Crystl Bustos, who also hit a home run, said: "We couldn't wait to get started. We were sick of practice."
The US have won every softball gold since the sport was introduced in 1996, and are hot favourites to make it four out of four.
Their win over Venezuela was their 14th consecutive Olympic victory, a streak of dominance stretching back to a 2-1 round-robin loss to Australia at the 2000 Sydney Games.
Of those 14 wins, 13 have been shutouts, the Americans out-scoring their opponents 74-1.
"We're not trying to put on a show, we're trying to play the game the way we know how to play," said US coach Mike Candrea.
"USA softball plays the game hard, plays the game aggressively, playing it smart, and that's my concern. If it was a great show, I hope we have more great shows throughout the week."