Mayweather v McGregor - a farce, or the biggest fight in combat sports ever? Next weekend, what's predicted to be the biggest-grossing boxing match of all time is being staged in Las Vegas. And it's not even for a title. In one corner will be Floyd Mayweather, an unbeaten fighter regarded by many as the greatest defensive boxer ever. In the other will be a man who has never even competed in a single professional boxing match. So who is Conor McGregor and how did he talk himself into this fight? BBC Ireland Correspondent Chris Buckler reports from Dublin.