Pari - Olympic champions Fiji started the defence of their world title with a 24-17 victory over Japan on the opening day of the 50th edition of the Dubai Sevens tournament on Thursday.
Captain Jerry Tuwai, who was a gold medallist in Rio in 2016, scored one of four tries for the Flying Fijians who pipped the US to claim their fourth global crown in June.
Elsewhere Mike Friday's Americans beat Ireland 24-19, who have been promoted as a core team for this season's circuit.
New Zealand, winners in Dubai last December, hammered Wales 36-7 as Tone Ng Shiu, Kurt Baker and Ngarohi McGarvey-Black all crossed twice.
South Africa came from behind to claim a 17-12 victory over Kenya as Rosko Specman and Seabelo Senatla dotted down in the second half after trailing by seven points to the Shujaa at the break.
On Friday, the Pacific Islanders face Argentina and France for a place in the main quarter-final draw.
In the women's tournament Stacey Waaka and Huia Harding scored two tries each as defending world and Dubai champions New Zealand hammered Japan 48-0.
The Black Ferns play England and France on Friday in the second leg of the women's series after the US won on home soil at Glendale in October.