World number two Roger Federer [Images] said he is not going to analyse his recent defeats by Rafael Nadal [Images] and Andy Murray [Images] and believes an aggressive approach would bring him back to winning form.

Federer has not won a Masters title since 2007 and has lost his last five matches against Nadal, including the five-set thriller in the Australian Open [Images] last month.

After that disappointment, the Swiss player lost out to Murray in the semi-finals at Indian Wells last week.

"You could analyse in a big way but at the same time, it just happens sometimes. Of course I was disappointed at the way the match ended in Australia [Images] and also in Indian Wells but it is not the end of the world," he told reporters at the Sony Ericsson Open.

"It doesn't really play on my mind a whole lot because I go out there and try to play every point as tough as I can."

Federer, who begins his campaign in Miami [Images] against American journeyman Kevin Kim, says he has only one route to beating Nadal.

"I've tried many different things against Rafa. Usually it is the aggressive playing style that makes me beat Rafa, especially on the hard courts. I haven't had many chances on hard courts against him, I've had so many more on clay," he added.

"On hard court I have to play aggressively against him. There is no way around that. I know how I have to play him. I've beaten him enough to know," said the 27-year-old.

Federer, who has 13 Grand Slam titles, rejected the suggestion that a back problem is seriously hampering him.

"The back is okay, I wish it was better but it's not really handicapping me when I am playing. It's not that bad," he said.

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