Samoa joined Japan on four points at the top of Pool B as Tusi Pisi showed real vision with the boot to create two tries in a comfortable 25-16 victory over the United States.
In addition to kicking four penalties, Pisi’s superb grubber kicks created tries in either half for Tim Nanai-Williams and Ofisa Treviranus.
Nanai-Williams, cousin of New Zealand's Sonny Bill Williams, showed his sevens athleticism as he dived over to score in the 20th minute while Treviranus was in the right place when the ball ran loose in the 46th minute.
USA fly-half Alan MacGinty opened their account with a penalty after 31 minutes and was heavily involved in a break from their own 22 which led to captain Chris Wyles touching down after 33 minutes.
Wyles’ try cut the deficit to 11-8 but, even though replacement Chris Baumann burrowed over in the 74th minute, USA were never as close again.