Updated

Two-time defending gold medalists Misty May-Treanor and Kerri Walsh remained unbeaten in preliminary action of the women's beach volleyball tournament at the London Games, winning in straight sets on Monday.

On what was May-Treanor's 35th birthday, the Americans posted a 21-14, 21-19 win over Marketa Slukova and Kristyna Kolocova of the Czech Republic to improve to 2-0 in Pool C play. The U.S. duo have won 31 straight sets without a loss in Olympic play.

Zhanh Xi and Xue Chen, who won bronze in the women's tournament four years ago in Beijing, rebounded from a loss in their opening game to defeat the Swiss team of Simone Kuhn and Nadine Zumkehr in three sets.

On the men's side, the U.S. team of Jake Gibb and Sean Rosenthal were handed a two-set loss by the Polish duo of Grzegorz Fijalek and Mariusz Prudel.

Group play continues for both men and women on Tuesday at Horse Guards Parade.