Federer slams critics after squeezing past Serra in Miami

ROGER Federer stepped onto the offensive after moving into the fourth round of the $4.5million Sony Ericsson Open, slamming suggestions he is only interested in the majors.

HITTING OUT: Roger Federer insists he is interested in more than just the majors after moving into the fourth round in Miami (Getty Images)

Federer was not at his liquid best but had far too much in his armoury for France's Florent Serra, chalking up a 7-6 (2), 7-6 (3) victory - saving his best for the high-intensity tie-breaks.

The Swiss world number one and Serra each racked up three breaks of serve apiece as Federer continued his indifferent form that saw him beaten in the final of the BNP Paribas Open in Indian Wells by Marcos Baghdatis.

But after keeping his pursuit of a third title in Miami alive, the 16-time grand slam champion rubbished claims it is only the four showpiece tournaments that motivate him.

"The ones who think I am only interested in the grand slams could not be more wrong," said Federer.

"I thought I was playing pretty well in Indian Wells against Baghdatis but all of a sudden he was playing really well and the next thing I know I was out.

"But that's the way it goes. There can be plenty of swings in momentums - it shows that the depth in men's tennis s great at the moment."

Federer is not the only top ten player struggling for form at the moment and in Miami, defending champion and British number one Andy Murray has already fallen by the wayside.

Also out is world number two Novak Djokovic, and while former world number one Rafael Nadal remains in the draw. Federer is well placed to strengthen his position at the summit of the global standings.

"This tournament will be good for my ranking because a lot of my rivals have lost here already - it just goes to show how many good players there are at the moment." Added Federer.

"But it's important for me to do well here. I plan to have a break after this tournament so I want to do well to set me up for the clay season and then go all the way through to Wimbledon."