Both Floyd Mayweather and Manny Pacquiao have hinted at a rematch of the richest fight in history.

But four years after Mayweather outpointed his great rival with consummate ease, we are no closer to a second installment.

The easiest avenue to a rematch would have been a clause in the contract for the initial bout.

But given that fight took more than five years to negotiate, it is understandable that neither side had the stomach for more talks.

Indeed, Pacquiao's then promoter Bob Arum said at the time: "We were negotiating this fight and the subject of a rematch never came up.

Floyd Mayweather beat Manny Pacquiao in 2015

"I think both sides realise that if we started working a rematch clause out that instead of having a press conference today, we'd still be negotiating."

Several months before the warring duo finally touched gloves, however, Pacquiao's trainer Freddie Roach said he believed Mayweather did want a rematch clause - in the event he lost.

"My understanding is that Floyd is insisting on the rematch if Manny beats him, which I believe he will. That's okay with us," said Roach, "And why not, given the huge amount of money which would be involved?"

Had Pacquiao won, you can guarantee Mayweather would have insisted on another shot at the Filipino, which would have earned both men another nine-figure pay day.

But a member of Pacquiao's team said, quite sensibly, that their man did not want to agree a second fight on the same split as the first, namely 60-40 in Mayweather's favour.

And so far there has been no rematch

"That's what Manny doesn't want," said Dioceldo Sy. "They may later be tied to a 60-40 split if contracted for a trilogy or rematch.

"At least after one fight, a rematch can be quite different, so Manny says, 'just slowly'."

After Mayweather reached 48-0 with victory over Pacquiao, he reached his half century with wins over Andre Berto and Conor McGregor .

Pacquiao meanwhile has won five of his subsequent six fights with his sole defeat coming against Jeff Horn two years ago.

Most recently he earned a split-decision win over Keith Thurman to cement his position as one of the best pound-for-pound fighters in the world.