Five-time champion Roger Federer beat Germany's Philipp Kohlschreiber to reach the US Open fourth round. Federer claimed 6-3, 6-4, 6-4 victory. The Swiss will next play 13th seed John Isner of the United States.In the women's draw, Czech fifth seed Petra Kvitova routed Slovakia's Anna Karolina Schmiedlova 6-2, 6-1 to book a last-16 meeting with Briton Jo Konta. Konta beat German 18th seed Andrea Petkovic 7-6, 6-3 to extend her remarkable winning run to 16 matches. The British number two had never been past the second round at a Grand Slam before this week. Her fellow Briton Andy Murray plays Brazilian number 30 seed Thomaz Bellucci in his third-round match later.