Top-ranked Novak Djokovic and Roger Federer, seeking his sixth U.S. Open title, made it into the fourth round Saturday with victories in New York. Djokovic continued his stunning year by blasted past Russian Nikolay Davydenko, 6-3, 6-4, 6-2, improving to 60-2 on the season. The Serb star is seeking to become the sixth man to win three Grand Slam titles in the same year in the Open Era -- he has already won the Australian Open and Wimbledon. Federer, meanwhile, prevailed over Marin Cilic of Croatia 6-3, 4-6, 6-4, 6-2, improving his career record in Flushing to 59-6. The 30-year-old Swiss superstar dropped the second set and was knotted at 4-4 with Cilic in the third when he broke the Croat for a 5-4 edge and cruised the rest of the way. Also Saturday, American Mardy Fish stayed hot by gutting out a tough 6-4, 7-6 (7-4), 7-6 (7-3) victory South African Kevin Anderson that lasted 3 hours, 20 minutes at Armstrong Stadium. Fish captured the U.S. Open Series heading up to the U.S. Open. Czech Tomas Berdych, meanwhile, retired with a shoulder injury while trailing 20th-seeded Serb Janko Tipsarevic, 6-4, 5-0. Former No. 1 Juan Carlos Ferrero, meanwhile, also cruised into the round of 16 in a walkover when his opponent, 31st-seeded fellow Spaniard Marcel Granollers, retired down 6-1, 4-3.