Lisa Raymond, Liezel Huber book quarter-final spot

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.