The Pacific neighbours will face-off on Friday, 31 March, at 8.28pm (Samoa Time).
A day later, the Brian Lima coached side will take on Argentina before their final pool game against Canada.
The first cup quarter-final match is at 3.02pm (Samoa Time) on 2 April.
Fiji is yet to win a tournament on the HSBC World Rugby Sevens Series this year and sits on fourth place on the points table.
Samoa is currently in sixth place.