Roger Federer has insisted that he is back to full fitness and capable of winning this year's US Open.

The Swiss had been struggling with a back problem, but is determined to silence his critics at the forthcoming grand slam.

"Clearly when I come here I don't just look at trying to make quarters, you know," he told reporters. "I'm clearly here trying to win the tournament, but it starts at the very beginning and that's Monday."

The 32-year-old is seeded seventh for the tournament following a troubled year on the court, but was quick to downplay his current world ranking.

"The rankings fluctuate a lot, especially if you don't play so well," he said. "If you play great you move up or go down rather quickly," he added.

"The ranking actually itself is secondary but I have looked at the rankings my whole life. I used to be incredibly excited on Monday seeing how many spots my ranking went up or down.

"Usually it was more excited that it was going up. The older you get the less you pay a bit of attention about it. But nevertheless, clearly want to move up from here."

Federer will take on Slovenia's Grega Zemlja in the first round of the US Open.