Conor McGregor has been knocked out during a sparring session ahead of his highly-anticipated showdown with Floyd Mayweather , according to Jessie Vargas.

Vargas, a two-weight world champion, made the claim during an interview with Villainfy Media and named Essex-based MMA fighter Bradley Wheeler as the man who did it.

McGregor has just finished a four-date four-press conference tour with Mayweather to promote the fight in Los Angeles, Toronto, New York and London, with the two fighters hurling controversial comments at each other over the microphone.