Floyd Mayweather Jr. is set to fight an undetermined opponent on Sept. 13.

Mayweather Promotions chief executive Leonard Ellerbe told ESPN, "Floyd will go on Sept. 13 and we looking at who he's going to fight and where he is going to fight. Obviously, Las Vegas is his home and the MGM Grand is always the leading candidate but we will take a look at our other options."

The big question now is who would the pound-for-pound king fight next?

Mayweather's last fight with Marcos Madiana for the unification of welterweight world titles was quite a walk in the park, but they are not discounting the possibility of a rematch since the latter put on a good show.

Amir Khan, the classic pugilist British thumper already expressed his desire to go up against Mayweather.

While he is the next logical opponent for the boxer with 46-0 record, Khan is a Muslim and won't fight during Ramadan.

Since the match is slated on September, Khan may be out of the mix for now.

After his 2012 loss against Mayweather, Cotto is eager for a rematch, especially after his big win against Sergio Martinez recently.

Boxing fans would love and pay top dollar to see Mayweather vs Pacquiao bout, and this could be historic, too.

However, technicalities and Mayweather seemingly not wanting to risk his undefeated career streak on the line are some of the reasons.

In an interview with Daily Mail, Pacquio's trainer already discounted the possibility of the fight ever happening in the future.

Freddie Roach said, "Manny and Floyd should have happened a couple of years ago when both were in their prime. I think Mayweather wanted the fight then. Later when we put them on the phone together Floyd said he wanted blood testing and 60 per cent of the money."

He added, "Manny said yes to both but then we never heard back from Floyd again."

Mayweather tops the list of Forbes' highest paid athletes in 2014, with total earnings of $105 million from winnings alone, making his last fight with Canelo Alvarez in September 2013 set records for highest pay per view, live gate and total revenue in the recent years.