American top seeds Lisa Raymond and Liezel Huber are safely through to the second round of the women's Olympic doubles thanks to a straight-sets victory over Agnieszka and Ursula Radwanska of Poland.
Raymond and Huber broke their opponents' opening service game before holding serve to see out the first set 6-4.
The Radwanska sisters offered more resistance in the second but were eventually undone 7-3 in the tie-break.
The American team will meet either the German pairing of Julia Goerges and Anna-Lina Gronefeld or Slovakians Ekaterina Makarova and Elena Vesnina in the last eight.
