USA captain Dave Hodges expressed delight at his team's 39-26 win over Japan in Gosford.
Mike Hercus was full of running on a night he scored 19 points
Hodges, playing his 50th cap, led the Eagles to their first World Cup win in 15 years.
In that time they have lost 10 matches in a row, a record he was glad to end.
"It feels great to get that win after so many years," he said. "We let the game get away from us a bit, but every time we got back on the pattern and kept going hard."
The USA came into the tournament with the intention of winning two matches in the pool stages.
After their 19-18 defeat to Fiji, when Mike Hercus missed with a last-minute conversion to win, this was due reward for a team that has impressed onlookers in Australia.
Hercus made amends with the first try of a match in which he finished with 19 points.
"We've accomplished our first goal now, a little bit further in than we wanted to but it feels really good," Hodges added.
"I was a little bit worried in the second half because I felt the game was getting away from us, we tried to get a little bit fancy at times.
"Our aim was to run straight and hard throughout the full 80 minutes and when we managed to do that, it paid off.
"Thankfully we were able to establish ourselves in the game in the latter stages and got the win.
"It is a great feeling, not because of my 50th cap, but because we have finally managed to win another World Cup game."
Coach Tom Billups saved special praise for Hercus, who he described as a "very talented footballer".
"Unfortunately in our first two pool games we weren't able to provide him with the platform to play the kind of game that he can bring to us," he said.
"Rugby World Cup victories have been hard to come by, and
I know that it hasn't been for lack of want.
"I told the team they'll be able to etch their names in the book now."