Boxer Floyd Mayweather and mixed martial arts superstar Conor McGregor have confirmed they will fight in Las Vegas on 26 August.

Undefeated Mayweather, 40, is coming out of retirement for the clash after being constantly challenged and goaded by the brash 28-year-old from Ireland.

McGregor is the biggest draw of the UFC (Ultimate Fighting Championship) and the current lightweight champion – but his sport allows kicking and grappling.

The fight – under boxing rules – is bound to draw huge interest from fans and massive pay days for the two fighters.

Both men had previously said they wanted $100m (£78m) each for the fight and negotiations have gone back and forth for about a year.

Mayweather, considered one of boxing’s all-time greats thanks to his defensive skills, posted on his Instagram account: It’s official! alongside an promo image of the two men.

McGregor, with a record of 21 wins and three losses, tweeted: THE FIGHT IS ON.

However, in what appeared to be a swipe at his opponent’s age, he instead posted a photo of Mayweather’s father, Floyd Mayweather Sr.

It will be McGregor’s first professional boxing match.

Neither specified the Las Vegas venue that will host the fight.

Mayweather is risking his prized undefeated record but McGregor’s taunts, a return to the limelight and a huge payout look to have proved too tempting.

The American will also be aware that a win would take him ahead of the legendary Rocky Marciano, who also retired with a 49-0 record.

McGregor will be the overwhelming underdog, but win or lose the showdown is likely to propel him into the consciousness of many non-fight fans around the world.

(c) Sky News 2017: Floyd Mayweather and Conor McGregor confirm Las Vegas ‘superfight’