Roger Federer has been experimenting with new tactics that he hopes will enable him to fulfil his 2009 goals of regaining the world number one ranking and equalling Pete Sampras’s record of 14 Grand Slam titles.

The Swiss was ousted from the top of the rankings by Rafael Nadal last August and his aura of invincibility was broken by defeat in the Wimbledon final before he silenced his doubters with victory in the US Open - his 13th Grand Slam crown.

The 27-year-old said he was feeling much fitter at the start of this season compared to last year where he was recovering from a bout of glandular fever.