World number three, Stan Wawrinka on Thursday said that fellow Swiss tennis legend Roger Federer was back to his best and can become World No. 1 again. Wawrinka, who is preparing for the Miami Masters, said, “He’s playing really well, what is different maybe is he is playing closer from the baseline, using less his slice, he is using more topspin, putting more pressure all the time, returning better that’s the difference I feel.”