Kessy and Ross marched through their three group matches without losing a set and then defeated Simone Kuhn and Nadine Zumkehr of Switzerland 21-15, 21-19 to open the knockout phase of the tournament.
The Americans will not learn their quarterfinal opponents until Saturday when teams from Brazil and the Czech Republic meet in the round of 16.
Two-time defending Olympic champion Misty May-Treanor and Kerri Walsh Jennings are in the other half of the bracket from Kessy and Ross and those teams could only meet in the finals.
May-Treanor and Walsh Jennings will play in the round of 16 on Saturday against Marleen van Iersel and Sanne Keizer of the Netherlands.
In the opening knockout games in the men's bracket Friday, Paolo Nicolai and Daniele Lupo of Italy defeated Americans Todd Rogers and Phil Dalhausser in two sets.
The other U.S. men's team in the knockout round, made up of Jacob Gibb and Sean Rosenthal, will be in action Saturday.
Dog comes home gnawing on human bone
Julius Randle breaks leg during NBA debut