By Edward Chaykovsky

Last September, former five division world champion Floyd Mayweather Jr. (49-0, 26KOs) retired from the sport after 19 years of competition.

His last fight was a twelve round unanimous decision over former two-time welterweight champion Andre Berto at the MGM Grand in Las Vegas.

Not everyone believes Mayweather is gone for good.

There are a lot of people who expect him to return at some point to go for his 50th win in order to surpass the unbeaten streak of heavyweight legend Rocky Marciano.  

At the time of his retirement, Mayweather was the WBA/WBC world champion at welterweight and junior middleweight. All of those titles have since been vacated.

Mayweather is not fighting on Cinco De Mayo weekend for the first time since 2011, as Saul 'Canelo' Alvarez will return on May 7th against Amir Khan.

Former IBF champion Shawn Porter (26-1, 16KOs) is deep in training for his very important fight against WBA welterweight champion Keith Thurman (26-0, 22KOs), scheduled for March 12th.

Porter did not reveal specifics, but he's heard some discussion of a Mayweather comeback.

Porter, Thurman and Mayweather are all advised by powerful manager Al Haymon.

He believes Mayweather will be watching his upcoming bout with Thurman - with the idea of potentially facing the winner at the end of the year.

"I don’t think he’s retired. I’ve heard things about him coming back once more, but only once more. He’s tied the record and he’s trying to break the record, but at the same time, I think he’s gonna watch this fight and whatever happens between Keith and I, and if he feels like he can beat one of us, he’ll come back. I think if he doesn’t feel like he can beat one of us, he won’t come back. We’ll see what happens, I feel like March 12th is a very deciding factor for not only the rest of 2016 but also the years to come," Porter told On The Ropes Boxing Radio.