The All Blacks Sevens came out of the blocks fast, racing out to an early lead through Scott Curry. Ngarohi McGarvey-Black's conversion looked like it might end up being an important one when American speedster Perry Baker sped down the left-hand touchline to score, with the subsequent shot at goal sprayed wide.
However, the hosts hit back almost immediately with a terrific solo effort from Kurt Baker, with the conversion extending the lead to nine points at the break.
After somewhat of an arm-wrestle in the second half, a powerful run saw Tim Mikkelson carry defenders over the tryline and plant the ball in the corner to seal the win, with Sam Dickson adding another on the final hooter.
Speaking after the win, Mikkelson said they knew what they were in for against the States.
"They got second in the World Series last year. They're an extremely consistent team, with the big boys up front and that speed out wide. We knew if we could start really well against Wales and build something, the last game of the Hamilton Sevens day one, we all just wanted to get up because we've all got our families in the crowd.
"We talked about winning our pool because there are no quarter-finals. We got two wins today so we're on track if we can get up against a good Scotland team tomorrow.
"We played them in the quarter-finals over in Cape Town and they really came back. They're the same sort of boys (as the USA team), really big with some pace, so if we can keep defending the way we are we've got a good shot."
With Wales and Scotland also in their group, and suffering heavy losses against the All Blacks Sevens and the USA respectively in their openers, it's hard to see either getting the better of their opponents in the final game of pool play.
Elsewhere, Fiji cruised through their first two matches to finish the day top of their pool with the semifinals in sight, while England and Canada topped their respective groups.
