We should point this out from the start... This claim remains entirely unconfirmed but, apparently, Conor McGregor has already been knocked out in fight camp.

'The Notorious' is focusing exclusively on striking in preparation for his upcoming lucrative super-fight with Floyd Mayweather, which will come as the Irishman's first ever professional boxing outing. McGregor is not treating the bout as a money grab, however. The reigning UFC lightweight champion has drafted in legitimate sparring partners to prepare him for the challenge of the 49-0 legend. Dashon Johnson and Tiernan Bradley have already been pictured working with the Dubliner, while he is planning to utilise the experience of former two-weight world champion Paulie Malignaggi when he brings his training camp to the United States. As expected, McGregor is putting in more rounds of sparring than he's ever done before. "We're doing four times the amount of sparring for this camp than we would do for a regular MMA camp. That's a huge amount of extra rounds," head coach John Kavanagh recently told the Mac Life. https://twitter.com/TheNotoriousMMA/status/879473665867264000?ref_src=twsrc%5Etfw&ref_url=https%3A%2F%2Fwww.joe.co.uk%2Fsport%2Fconor-mcgregor-sparring-partner-floyd-mayweather-paulie-malignaggi-131663 "To be able to do four times the amount of sparring, the progress we're seeing - because after each session we do a video analysis - the progress we're seeing from one session to the next." And apparently, one of those sessions resulted in the 29-year-old being knocked unconscious, according to former WBO welterweight champion Jessie Vargas. We don't know how reliable Vargas' sources are but he's adamant that McGregor was knocked out in sparring as he played down his chances of getting the best of Mayweather in August. https://www.youtube.com/watch?v=7u9DZ5HQF40 "He got knocked out in sparring already, man!" Vargas told VillainfyMedia. "The boxing world is small, it's a small circle." It would not exactly be surprising if rumours like the above were spread just to tarnish McGregor's reputation as the boxing community is not all that happy that an outsider has arrived to seal one of the biggest paydays in the history of the ring. So maybe take Vargas' comments with a pinch of salt.