It's Official: Floyd Mayweather faces Manny Pacquiao in a $250m mega-fight on May 2...

The richest fight in history is officially on after Floyd Mayweather posted a signed copy of his contract with Manny Pacquiao on social media on Friday night, setting in motion the formal countdown to a $250million (£160m) blockbuster on May 2.

A fight that has been five years in the making will be staged at the MGM Grand in Las Vegas, pitting Mayweather's hyped unbeaten record against one of the most effective, exciting punchers of their generation.

Feuds have dominated every stage of the stuttering discussions over the past years, with arguments over drug testing and financial splits.

Set to be the richest fight in boxing history, the purse is expected to start at $250m - with Mayweather guaranteed a minimum $150m and Pacquiao's share at least $100m.

Manny Pacquiao vs Floyd Mayweather mega fight

With Mayweather understood to have commanded the 60-40 split of the purse, the fight will occur – with an autumn rematch clause believed to have been written into the deal by Mayweather.

The 37-year-old is understood to have been the dominant figure throughout negotiations – right up to getting his wish to announce the fight, which he did via - a social media site in which he has a stake in.

He posted the contract along with the comment: 'What the world has been waiting for has arrived. Mayweather vs. Pacquiao on May 2, 2015, is a done deal. I promised the fans we would get this done, and we did. We will make history on May 2nd. Don't miss it! This is the signed contract from both fighters.'

Mayweather shared official signed contract
(Image above: Mayweather shared the official signed contract for the fight via his Shots social media account on Friday)

The fight will be a joint pay-per-view event shown on Showtime, the channel Mayweather is contracted to, and HBO who have the deal to show Pacquiao's fights.

According to reports, every room in the MGM Grand sold out within three minutes of the fight being announced.

Mayweather, the WBA and WBC welterweight world champion, and winner of all of his 47 fights, said: 'I am glad my decision to meet with Manny and discuss making this fight happen helped get the deal done,' said Mayweather.

'Giving the fans what they want to see is always my main focus. This will be the biggest event in the history of the sport. Boxing fans and sports fans around the world will witness greatness on May 2. I am the best ever, TBE, and this fight will be another opportunity to showcase my skills and do what I do best, which is win.

'Manny is going to try to do what 47 before him failed to do, but he won't be successful. He will be number 48.'

Pacquiao, the WBO champion who has been defeated five times in 64 fights, said: 'I am very happy that Floyd Mayweather and I can give the fans the fight they have wanted for so many years.

'They have waited long enough and they deserve it. It is an honour to be part of this historic event. I dedicate this fight to all the fans who willed this fight to happen and, as always, to bring glory to the Philippines and my fellow Filipinos around the world.'

Pacquiao's trainer Freddie Roach said: 'Floyd should enjoy being the A-side while he can because on May 2, Manny is going to put him on his backside.'

Manny Pacquiao twitter message to his fans

The pair, who both beat Ricky Hatton before the Mancunian retired, have long been considered the two best fighters of their generation and boxing fans have been itching for them to get in the ring for years.

This saga, which has frustrated fans as much as it has begged a question of how the sport's organisational make-up could fail to enforce such a fight, had come close to fruition in 2010. That is when contracts were drawn before the fight collapsed because Pacquiao refused to give blood and urine samples at random right up until the day of the event.

His argument was that giving blood so close to his 2005 fight with Erik Morales had caused his defeat. The bitter fallout and Mayweather's apparent insinuations about Pacquiao's refusal to submit to the USADA testing led to the latter taking legal action.

Since then, the hopes have peaked and faded but with no meaningful action. But after the fighters met face-to-face last month at a basketball match in Miami, talks escalated quickly. Multiple times each week reports surfaced that the fight had been confirmed, only for a denial to follow, often from Mayweather's camp.

Manny Pacquiao I can beat Floyd Mayweather