Andy Murray
Murray says he has been a victim of double standardsGetty Images

Andy Murray has accused his critics of double standards in a fiery message on Twitter after Rafael Nadal survived cramp to defeat Tim Smyczek in five sets at the Australia Open on Wednesday (21 January).

The 14-time grand slam champion received treatment for stomach cramps mid-way through his gruelling four hour 12 minute win over American Smyczek, who came close to inflicting upon Nadal his earliest ever exit in Melbourne.

Nadal, who underwent surgery to remove his appendix last year which forced him out of the final two major tournaments of season, was highly praised for coming through the second round test and Murray has taken exception to the treatment of the Spaniard.

Murray was labelled a "drama queen" by former British No.1 woman Virginia Wade after he struggled through back spasms to defeat Jarkko Nieminen at the French Open in 2012, while the Scot suffered from cramp during his US Open win over Robin Haase last August.

And the former Flushing Meadows and Wimbledon champion stated on Twitter: "When I cramped and won in the US open last year I was a "drama Queen, unfit, needs to see a shrink, faker" weird..."

The message represents the second time in the last five months where Murray has made waves on Twitter, after he declared his support for Scottish Independence on the eve of the polling stations opening in September.

However, his latest outburst is unlikely to distract from his impressive start to his Australian Open campaign where he has sauntered through to the third round, where he will face Portugal's Joao Sousa, without dropping a set.

Stiffer challenges face Murray should he reach the last 16, with Wimbledon conqueror Grigor Dimitrov, 17-time major champion Roger Federer, Nadal and Novak Djokovic all likely to stand between him and a third grand slam title.