Fiji scored five tries with debutant Alosio Naduva scoring his first try as well.
Fiji was leading 14-5 in the first half with tries from Amenoni Nasilasila and Mesulame Kunavula.
Looking at other results, England beat Spain 22-10, defending champion South Africa thrashed Papua New Guinea 50-0, France beat Wales 31-12, Argentina edged Kenya 7-5, New Zealand thumped Russia 61-0, Australia beat USA 26-19 while Scotland thrashed Canada 52-5.
Samoa will take on New Zealand and Russia this evening.
South Africa is the defending champion of the Sydney 7s.
