Bookmakers in Britain and Ireland face one of the biggest pay-outs in betting history if Irish MMA superstar Conor McGregor beats Floyd Mayweather in one of the most anticipated boxing fights of all time on Saturday night.

Since the fight was announced earlier this year, undefeated Mayweather has been odds-on to win – but his odds have been drifting in the build-up due to the volume of bets being placed on McGregor.

Mayweather, who has come out of retirement to fight, was a short as 1/33 but now is trading around 1/4 whilst McGregor began at 10/1 but is not down to 7/2.

OddsMonkey believes that a victory for McGregor would result in the biggest pay-outs in sporting history as the fight is set to be worth £300million in betting alone in the UK and Ireland.

“We have spoken to Bookmakers and seen betting patterns, and the odds in general – ideally they would have kept Mayweather at around 1/20 but given the amount of money going on McGregor they had to cut him and lengthen the American’s odds,” revealed OddsMonkey spokesman Peter Watton.

“We have been told that 8 out of every 10 bets on the fight, even up to 9 out of 10 with some Bookmakers, are going on McGregor and given this is the biggest boxing match in betting history you can imagine how much that is worth.

“Betting for this fight, worldwide – will easily go through the £500million mark and one thing is for sure, a McGregor win would cost the Bookmaking industry hundreds of millions in losses, they would be unprecedented.

“But let’s look past the hype, the chances of a McGregor win are so big – indeed his odds are wrong, they are way too short, but they have to be at that mark just on the money alone.

“Yes, Mayweather is a short price – but any value in this fight is with him, we believe there is only one outcome and so, Punters beware, don’t be blinded by the McGregor hype.

“This IS a one horse race, so anything you put on Mayweather is basically free money, and the Bookmakers agree – they don’t want you to back Mayweather – he is called Money for a reason.”