Seeking their third straight gold medal, May-Treanor and Walsh Jennings defeated Marleen van Ierse and Sanne Keizer of the Netherlands 21-13, 21-12.
Next up for the American beach volleyball stars will be Greta Cicolari and Marta Menegatti of Italy Sunday.
In the men's tournament round of 16, Jacob Gibb and Sean Rosenthal of the United States advanced past a Russian pair in straight sets and will face Martin Plavins and Janis Smedins of Latvia Monday.
Exploding whale video goes viral on Internet
Wisconsin business offering 'therapeutic cuddling' forced to close