Roger Federer defeated Philipp Kohlschreiber for the 10th time to reach the US Open last 16 on Saturday as Canadian golden girl Eugenie Bouchard suffered a potentially tournament-ending head injury.

Five-time champion and world number two Federer claimed a 6-3, 6-4, 6-4 victory over his 29th-ranked German opponent.

The 34-year-old Swiss star, hoping to become the oldest champion since Ken Rosewall in 1970, will next face US 13th seed John Isner, who progressed after Czech opponent Jiri Vesely retired with a neck injury after dropping the first two sets.

Bouchard, meanwhile, was facing a battle to make her scheduled last-16 clash with Italy’s Roberto Vinci on Sunday after injuring her head in a fall in the women’s locker room on Friday.

The 21-year-old Canadian star withdrew from the women’s and mixed doubles tournament on medical advice. 

Federer has now reached the fourth round in New York for the 15th year as he looks to return to the final for the first time since 2009.

Czech sixth seed Tomas Berdych, a semi-finalist in 2012, reached the last 16 for a fourth successive year by beating Spain’s Guillermo García-Lopez 6-7 (2/7), 7-6 (9/7), 6-3, 6-3.

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He next plays 12th seed Richard Gasquet, one of four Frenchmen in the last 16, who defeated Australia’s Bernard Tomic 6-4, 6-3, 6-1.

In the women’s event, two-time Wimbledon winner Petra Kvitova, the Czech fifth seed, eased past Anna Karolína Schmiedlova of Slovakia 6-2, 6-1.

She next faces British qualifier Johanna Konta, the world number 97 who beat German 18th seed Andrea Petkovic 7-6 (7/2), 6-3. Konta will be playing in her first Grand Slam fourth round.

Also advancing was Australia’s 22nd-seeded Samantha Stosur, who ousted Italian 16th seed Sara Errani 7-5, 2-6, 6-1.