Once the hunter, now the hunted, Andy Murray is braced for an all-out assault on his US Open title from rejuvenated Rafael Nadal and world No 1 Novak Djokovic.

Murray ended Britain's 76-year wait for a Grand Slam men's champion by triumphing in New York in 2012 and backed it up with his historic Wimbledon victory this year, the first by a British man since Fred Perry in 1936.

The Scot beat Djokovic to win the US Open 12 months ago and repeated the dose against the Serb at the All-England Club six weeks ago.