Undefeated 15-time world champion boxer Floyd Mayweather Jr. of the U.S. and Ultimate Fighting Championship (UFC) double champion Conor McGregor of Ireland are inching closer to a rematch of "The Money Fight," according to The Sun.

"It will be the last time Floyd ever steps in the ring so it is not one to miss. The deal is very close to being done. Personal terms have been agreed on both parties. It will be one final showdown. And, yes, records will be at stake. Floyd sees it as the end of the Mayweather era and the beginning of the Gervonta Davis era," The Sun reported.

The last time Mayweather Jr. and McGregor fought each other at T-Mobile Arena in Paradise, Nevada, on August 26, 2017, it created the second-highest pay-per-view buy rate in history of 4 million.

As the winner by technical knockout (TKO) in the 10th round, Mayweather Jr. made some $280 million from the match while McGregor received over $130 million.

The two legends are still negotiating the rules of the rematch, according to The Sun: "Conor will only take the fight providing Floyd is willing to put his professional record on the line – so the fight will not be an exhibition, it will be an official fight. It will be at 155lb. That's what we know so far."

"He believes it will be the biggest night boxing will have ever seen and has been saying 'People best be ready because it's going to be something spectacular.' There are arguments about the rounds at the moment with Conor's team wanting 10 rounds. But the deal and rights are certainly getting there," according to the British tabloid newspaper.

Mayweather Jr.'s last professional boxing bout happened in 2015 when he fought Andre Berto of the U.S. at the MGM Grand Garden Arena in Paradise, Nevada, on September 12, 2015. Having won by unanimous decision in the 12th round, Mayweather Jr. extended his record to 49-0. Though he only participated in exhibition fights, including "The Money Fight" that gave him the 50th win, in the following years, it didn't keep him from reaching $1.2 billion in career earnings in 2021.

It has been almost a year since McGregor fought anyone. He lost to Dustin Poirier by TKO in the first round at UFC 264 at T-Mobile Arena on July 10 after suffering a broken tibia. His weight reportedly grew to almost 190 pounds during recovery. If McGregor wants to fight Mayweather again, he will need to lose 35 pounds.

"Boxing is my first love in combat sports," McGregor told Sky Sports. "I had such a great time the last time I was out there. Obviously, my return will be in the octagon for UFC. That story is far from over, in fact it's just being written. It is just the beginning but boxing, for sure, I will grace the squared circle again in the future."