The Swiss world number one certainly earned his down time, tuning up his game over the last fortnight with a Montreal quarter-final -- his first event since winning Wimbledon -- and lifting a third trophy last weekend in Cincinnati, Ohio.

It was all part of the plan for Federer, who travelled with wife Mirka and their infants to North American just two weeks after the girls were born.

'I'm happy I was able actually to also come to Montreal,' said Federer, holder of 61 career titles including a record 15 Grand Slams. 'I got the muscle pain out there and got used to hitting big serves again.'

With his glandular fever of 2008 and his back problems now just fading memories, the top seed will be ready to aim for a sixth straight New York title.

'I have no back problem and pain, so that allows me again to play freely and focus on the way I want to play and not the way I have to hit the shot,' Federer said after his Cincinnati trouncing of Novak Djokovic.

'That's a big difference today from a few months ago.'