Top seed Nikolay Davydenko battled past Fabrice Santoro in the third round of the Pilot Pen Tennis Championships in New Haven.

The Russian was pushed hard in the first set but stuck to his task to win 7-5, before taking the second 6-3.

There was also a win today for Austria's Jurgen Melzer, who came through a tie-break in the first set and then lost the second before blitzing the decider 6-1 against Romania's Victor Hanescu.

In the women's singles second round, Russia's top seed Svetlana Kuznetsova needed three sets to get past Belgian qualifier Yanina Wickmayer. But number two seed Caroline Wozniacki, of Denmark, had a much easier time against Anastasia Pavlyuchenkova - winning 6-1 6-4.

Russia's Elena Vesnina beat previously in-form Australian Samantha Stosur 3-6 6-4 6-4.

Champion Caroline Wozniacki made a perfect start to the defence of her crown, the second seed denying Romania's Edina Gallovits a single game in a 6-0 6-0 victory.

There were further seeded casualties in the men's tournament, with wild card Rajeev Ram defeating fellow American Mardy Fish, the fifth seed and two-time runner-up, 6-3 6-3 while 10th seed Jeremy Chardy lost 6-7 (8/10) 7-6 (7/4) 6-1 to Florent Serra.

Seventh seed Igor Andreev ended the hopes of another American, beating Kevin Kim 6-3 6-1.

His countryman Igor Kunitsyn, the 14th seed, did not fare so well, though, going down 3-6 7-6 (7/3) 6-3 to Jose Acasuso.

Leonardo Mayer and Florent Serra completed the quarter-final draw after wins over Simone Bolelli and American wild card Rajeev Ram, respectively.

In the women's draw, third seed Flavia Pennetta was a 7-6 (7/1) 6-4 winner against Iveta Benesova but Agnieszka Radwanska retired at one-set all in her match with Virginie Razzano because of a right hand injury.

Sixth seed Marion Bartoli was another to pull out, the former Wimbledon finalist squandering match points on her own serve in the second set against Magdalena Rybarikova before calling it a day with the Slovakian leading 1-6 7-6 (7/5) 2-0.