Floyd Mayweather and Manny Pacquiao are already negotiating terms over a rematch, claim the New York Post.

The pair fought the richest fight in boxing history on May 2, which earned $600million.

Mayweather won on points after 12 relatively uneventful rounds in Las Vegas, to retain his unbeaten record.

Pacquiao complained of a shoulder injury in the aftermath of the bout, and has since had surgery on the problem.

Despite the fight not living up to expectations, a rematch would still earn each fighter more than any other bout.

“It’s already being negotiated,” a source told the New York Post.

"Pacquiao needs four months of rehab post-surgery, and three months to train.

“The fight will be the first event at the under-construction MGM–AEG Arena set to open next year.”

The news will come as a blow to Amir Khan, who had said he was confident of fighting the pound-for-pound king next.

Mayweather has said he only has one fight left before he will retire.

"There has been a lot of talk that it will be September when Mayweather is back in the ring again," Khan told BBC Radio 5 live.

"I am not going to chase it like I used to chase it. I am going to keep on fighting and if it comes, it comes."

Asked if there was a 50-50 chance of the fight taking place, he replied: "I think it could be better than that."