Cape Town - Third seed Roger Federer will be back in action under lights at the US Open against German veteran Philipp Kohlschreiber in the fourth round on Monday.
Following two five-set thrillers in the opening two rounds, the 36-year-old Federer looked far sharper and in control when easily beating Feliciano Lopez in the third round last time out.
Federer, who has a perfect 11-0 career over Kohlschreiber, has been struggling with back problems but feels those issues are under control and he can now focus on trying to win a record-extending 20th grand slam title.
"I needed to get over the fear of the back issue. Then I think the wobble I had in the second round was due to my preparation," he said.
"I think now I'm just trusting my movement better. My serve is there. My mind is there. I can finally focus on playing tennis and not so much about the past."
World number one Rafa Nadal, who is on track for a semi-final meeting with Federer should both keep winning their matches, takes on Ukraine’s Alexandr Dolgopolov.