Roger Federer: Only "something special" will beat me

World number one Roger Federer has warned his rivals that it will take "something special" to beat him at the US Open.

The Swiss player moved back to the top of the rankings following his success at Wimbledon earlier this year.

Having taken that form into Flushing Meadows, the 31-year-old has admitted that he is confident of winning his sixth title in New York.

"It's going to take something special from my opponent to win," he told reporters. "That's kind of the way it feels right now."

Federer will take on Bjorn Phau in round two this evening.