US Open singles fourth-round results from New York on Tuesday.
Men's singles results
4-Novak Djokovic (Serbia) beat 15-Radek Stepanek (Czech Republic)
6-1 6-3 6-3
10-Fernando Verdasco (Spain) beat John Isner (US) 4-6 6-4 6-4
6-4
1-Roger Federer (Switzerland) beat 14-Tommy Robredo (Spain) 7-5 6-2 6-2
12-Robin Soderling (Sweden) beat 8-Nikolay Davydenko (Russia) 7-5 3-6 6-2 (Davydenko retired)
Women's singles results
9-Caroline Wozniacki (Denmark) beat 6-Svetlana Kuznetsova
(Russia) 2-6 7-6(5) 7-6(3)
Yanina Wickmayer (Belgium) beat Petra Kvitova (Czech Republic) 4-6
6-4 7-5
Melanie Oudin (US) beat 13-Nadia Petrova (Russia) 1-6 7-6 (2) 6-3
Kateryna Bondarenko (Ukraine) beat Gisela Dulko (Argentina) 6-0 6-0
