This is a meeting of the smallest and largest competing nations in this tournament.
The USA has one of the world's biggest populations and the Cook Islands, with just 20,000 inhabitants, has one of the tiniest.
Size does not account for strength in this meeting, however, and the Cook Islands are heavy favourites.
The South-Sea Islanders have the greater experience, while the USA are making their World Cup debut at Bristol's Memorial Stadium and are widely considered to be the weakest team of all.
Whoever wins this match will go straight to the top of Group D after Wales lost their opener to Italy on Saturday at the Millennium Stadium.