'Who's John Buchanan?', asks Kevin Pietersen

Star England batsman Kevin Pietersen, who has not been in form of late, has laughed off criticism aimed at him by former Australian cricket team coach John Buchanan, and described the latter as "a nobody."

Buchanan, who won three out of four Ashes series during his six-year stint with Australia, described Pietersen as potential weak link, which the hosts could exploit when the battle for the famous urn begins in Brisbane on November 25.

The 57-year-old said Pietersen had the potential to be "a major problem" if he did not halt the alarming slump in form which has seen him go 27 Test innings without a century.

The Sydney Morning Herald quoted Pietersen, who will fly out with the rest of the England squad to Australia on Friday, as retorting: "I didn't react to it (Buchanan's comments) because it was strange that he made headlines.

I'm not interested in what he has to say. Who is he? He's a nobody.

"He had the best team to coach in the history of cricket. Anyone could have coached that team. He has done nothing else solid so I won't even take it with a pinch of salt," he added.