Criticism plagued undefeated boxer Floyd Mayweather Jr. after he chose the considerably "weaker" Andre Berto as his opponent for his September 12 match.

An interesting theory recently surfaced claiming that the American boxer is just using Berto as a "tune up" fight for a possible rematch with Manny Pacquiao.

ESPN's Stephen Smith discussed in an analysis that Mayweather may just be preparing for another fight with Pacquiao or another stronger opponent.

"I've never believed [Mayweather was going to retire in September]. I don't believe that. I think Mayweather knows that. I think Mayweather is using this [fight with Berto] as a tuneup, and then he's going to give Manny Pacquiao a rematch," Smith said in a Yahoo! Sports report.

He even likened the fight to the Pacquiao versus Chris Algieri match, which he said was another tuneup.

"It's almost one of those things where it's a tuneup, it's going to be perceived as a cake-walk in a lot of people's eyes. And he's like, 'I'm Money Mayweather, I'm giving you me on free TV. You don't have to pay for it at all. And then I'm going to come out of retirement and I'll fight a Manny Pacquiao, or a Miguel Cotto if Cotto is lucky enough to beat Canelo Alvarez," he added.

Mayweather initially said that he would give Pacquiao another match opportunity but then changed his mind.

He even bashing the Filipino boxer for allegedly using his shoulder injury as an excuse for losing their May fight.

Last week, TMZ reported that the camps of Mayweather and Berto have already reached a deal, and that the fight will happen on September 12 in Las Vegas.

Speaking to the entertainment news portal, Haitian-American fighter Berto said he is happy to be given the opportunity to fight Mayweather.

"It's a pleasure and honor to be in this position and I'm looking forward to capitalizing on every moment of it," Berto said.

 Washington Post added that the fight between Mayweather and Berto could be a free fight aired by CBS.

The decision to offer the fight for free could have been due to the "disappointing" fight between Mayweather and Pacquiao last May.

Dubbed "The Fight of the Century," it was largely seen by critics as barely even close to that.

In preparation for the fight, Daily Mail said Mayweather has been training inside his gym with him even smiling beside his title belts.

"Included in that collection was the $1million diamond and gold encrusted, emerald green WBC belt which he gained after defeating Manny Pacquiao," added the same report.

Daily Mail also reported that Mayweather has been pushing himself to the limits in his workouts.