James Mortimer 13.Oct.2012Getty Images
Mark Jackman crossed for two tries in the first half, with Tomasi Cama converting both, before the Americans gave the reigning champions a fright in the second half.
US speedster Carlin Isles, rated in the Top 100 of the world over 100m, with a personal best of a wind assisted (+3.2) time of 10.13 in Texas earlier this year - scored a blinding try which gave the underdogs a sniff against the All Blacks Sevens.
Gareth Williams-Spiers, despite some fierce attention from the defence, managed to score the match winner with barely a minute to play.
New Zealand play Canada and South Africa to round out pool play.
The opening match of the day proved how competitive the abbreviated form of the game can be, with England and Kenya drawing 14-14, while later Portugal came close to shocking Wales, before the Red Dragons closed out a 19-12 nailbiter.
Local team Australia defeated Tonga 31-14, while Fiji accounted for Scotland with the same scoreline.