Mayweather Sr. back as son's trainer

Pound-for-pound king Floyd Mayweather Jr.'s opponent for his May 4 return is still unclear, but he announced via Twitter on Wednesday night that whomever he fights at the MGM Grand in Las Vegas, his father, Floyd Mayweather Sr., will train him for the bout.

"Me & my trainer [my dad] back working together getting ready for May 4th," Mayweather tweeted. Mayweather also included a link of a photo of them together, presumably at his gym.

Mayweather and his father have had a well-documented rocky relationship for years. Floyd Sr. taught his son to box as a child and trained him in the early part of his professional career before going to prison, after which Roger Mayweather, Floyd Sr.'s brother, became Floyd Jr.'s head trainer.

Father and son have had various reconciliations over the years, and Floyd Sr. has been in some training camps in a limited role, although he was not around for Floyd Jr.'s two more recent fights: wins against Miguel Cotto last May and Victor Ortiz in September 2011.

It is unclear whether Roger Mayweather will remain part of the training team. He has medical issues, including diabetes, which might be a reason for the change.

Floyd Sr. has trained several notable fighters in recent years, working with Oscar De La Hoya, Ricky Hatton and Chad Dawson, among others.

There have been very public blow-ups between Floyd Sr. and Floyd Jr., including their memorable confrontation one day at the gym in the early days of the preparation for the Ortiz fight. Father and son engaged in a vicious, curse-ridden argument captured by HBO's "24/7" cameras. The episode ended with Floyd Jr. throwing his father out of the gym.

The younger Mayweather (43-0, 26 KOs), who holds titles at welterweight and junior middleweight, is expected to defend his welterweight belt in the May 4 pay-per-view fight. While most expect that he will face interim titleholder Robert Guerrero, Mayweather caused a stir last week when he said that the front-runner for the fight was fellow welterweight titlist Devon Alexander, despite the fact that the injured Alexander is under contract to face mandatory challenger Kell Brook in a bout that had been postponed just days earlier because Alexander suffered a biceps injury.

Golden Boy Promotions CEO Richard Schaefer, who promotes Guerrero and Alexander and has worked with Mayweather since 2007, has said that Alexander is not a candidate to fight Mayweather. Schaefer said he is working to reschedule the Alexander-Brook fight.