Defending champions Samoa came from 12-0 behind to beat Spain 19-12 Friday on the opening day of the US stop in the IRB Sevens World Series.
Captain Afa Aiono scored the winning try under the posts, delighting a vocal contingent of Samoa fans at Sam Boyd Stadium.
"It was really tough. Spain, they wanted to win the game, but I am happy with the boys, especially in the second half," said Samoa coach Faamaoni Lalomilo. "It is a second home, a big ground for Samoa, and the boys have to work hard for the fans too."
Samoa closed the night with a 12-7 Pool D victory over the United States, who had lost their opening match to Australia 26-7.
Spain rebounded with a 24-14 win over Australia.
In Pool A, Fiji won both of their opening-day matches, hanging on for a 14-12 victory over Scotland when Russell Weir missed a last-minute penalty drop goal.
England, champions at Wellington last week, lost both of their two matches -- 21-5 to Portugal and 26-17 to Fiji, who had two tries from Samisoni Viriviri.
In pool B, South Africa also ended the day with a perfect 2-0 record. They routed Uruguay 45-0 then followed up with a 17-5 victory over Canada.
"It's nice to get two on the board, we really wanted to start well, especially after last week," said South Africa's Paul Delport. "It was important. The guys aren't used to playing over three days so to build some momentum going into days two and three it is always great."
Eight remaining pool fixtures were scheduled for Saturday followed by quarter-final matches.
New Zealand also take momentum into the second day after conceding just five points in two day-one victories in Pool C.
Belgium Tuatagaloa scored two of New Zealand's three tries in a 21-0 victory over France. Ben Lam had a hat-trick in a 40-5 victory over reigning Rugby World Cup Sevens champions Wales.