Johannesburg: Defending champion Roger Federer kept his unbeaten record against Philipp Kohlschreiber intact after beating the German opponent to reach the quarterfinals of Swiss Indoors on Friday.
The 17-time Grand Slam champion claimed a 6-4, 4-6, 6-4 win over Kohlschreiber to improve his head-to-head record against the German to 11-0.
Reflecting on his win, Federer said that the support made the difference for him especially at the end of the match, Sport24 reported.
The Swiss said that although he had beaten Kohlschreiber a lot,it was always difficult against the German who is a tough opponent.
Federer, who has previously won six times in Basel, will next face Belgium's David Goffin for a semifinal spot.