World number seven Roger Federer has insisted that he is not bothered by the times of his matches at the US Open.
The Swiss advanced to the second round of the tournament after a 6-3 6-2 7-5 win over Grega Zemlja in one of several late-night matches on Thursday.
After the match, Federer revealed that he felt in great shape and was not fazed by the scheduling at Flushing Meadows.
"I felt great," Federer said. "Day session or night session it doesn't really matter when you play on Arthur Ashe Court."
Federer will face Carlos Berlocq in the next round.
