Fed's perfect 10

Five-time champion Roger Federer defeated Germany's Philipp Kohlschreiber for the 10th time in 10 meetings to reach the US Open last 16 on Saturday.

The world number two claimed a 6-3, 6-4, 6-4 victory to set up a clash against either US 13th seed John Isner or Jiri Vesely of the Czech Republic for a place in the quarterfinals.

Qualifier Johanna Konta became the first British woman in 24 years to reach the fourth round of the US Open by defeating German 18th seed Andrea Petkovic.

Australian-born Konta downed Petkovic 7-6 (7/2), 6-3 to book a last-16 matchup with Czech fifth seed Petra Kvitova, who routed Slovakia's Anna Karolina Schmiedlova 6-2, 6-1.

Canada's Eugenie Bouchard suffered a head injury when she slipped and fell in the US Open locker room that has forced her out of women's and mixed doubles and jeopardized her fourth-round singles match Sunday.

The 21-year-old from Montreal sustained the injury late Friday and US Open medical personnel continue to assess the severity of the injury. Medical staff recommended that Bouchard withdraw from the two doubles events and she went along with that suggestion.

Meanwhile a defiant Rafael Nadal vowed to fight on and restore his status as the game's most feared player after crashing to his earliest US Open exit in 10 years.

The 14-time Grand Slam winner was knocked out by Italy's Fabio Fognini, who pulled off a sensational 3-6, 4-6, 6-4, 6-3, 6-4 third-round victory. Nadal will finish the season without at least one Grand Slam title for the first time since 2004.