Even those closest to Floyd Mayweather Jr. don’t know if he’ll keep fighting

No one tells the impulsive Floyd Mayweather Jr. what to do.

So if he is sticking to the story that Saturday’s welterweight-title defense against mega-underdog Andre Berto is his final fight, the best thing to do is smile and nod.

Rest assured there are millions of reasons to believe he’ll be back.

The 38-year-old will likely tie Rocky Marciano’s 49-0 record Saturday night at the MGM Grand in Las Vegas. He’s a 50-to-1 favorite on the Showtime pay-per-view card.

“It’s a unique situation,” Showtime Vice President Stephen Espinoza said. “Boxing is a physically demanding and taxing endeavor and when someone decides they’ve had enough, it’s usually for a very good reason.

“In Floyd’s case, he’s been doing it for 19 years as a professional … and has virtually carried the sport for the last several years. So we wouldn’t want to push him to do something that physically or mentally he’s not prepared to do.”

There’s great interest in watching those closest to Mayweather and seeing how they straddle the line between good business sense and his personal stance that belies logic.

“As I’ve said a number of times, this will be Floyd’s last fight,” said Leonard Ellerbe, the president of Mayweather Promotions. Ellerbe says the fighter has at least three post-fight movie offers that will “occupy a lot of his time.”

Never mind that Mayweather has expressed less than half-hearted interest in those opportunities.

Other people close to Mayweather said they expect Mayweather to take a vacation at least through the end of the year, when he’s expected to travel, attend a slew of sporting events (mostly NBA games) and stay away from the trappings of boxing that irritate him — like publicity work.

“Anyone who tells you they know what he’s going to do is guessing,” said one boxing official connected to Mayweather-Berto who requested anonymity. “He’s the kind of guy who says, ‘I’m done,’ and it changes when it changes. None of us have any indication of there being a nod and a wink to a master plan.”

Mayweather threatened retirement after beating Oscar De La Hoya in 2007, did it again during his 21-month break before fighting Juan Manuel Marquez in September 2009, and he took a 16-month hiatus before fighting Victor Ortiz in September 2011.

Espinoza has coaxed six fights from Mayweather since May 2013, including the record-selling May victory over Manny Pacquiao.

“Selfishly, as boxing fans and as a network that’s been in business with him for almost the last three years, we don’t want this to end,” Espinoza said. “His performance is close to, or at, its peak. It seems like he has a lot left.”

Espinoza pointed to a segment in Showtime’s “All-Access” that showed Mayweather in February 2013 stating, “six fights in 30 months, then I’m done.”

So Showtime is selling the Berto bout as the last chance to see Mayweather.

“I have become convinced he believes his time is up,” Espinoza said.

Few others are buying that.

Four months from selling 4.4-million-plus pay-per-views at $100 apiece, this Mayweather bout against a former welterweight champion who has lost three of his last six fights is expected to be the champion’s worst-selling pay-per-view yet. He’s charging $74.95 for it in high definition.

As of Tuesday, MGM Grand was more than 2,000 tickets short of a sellout, offering tickets as travel-package incentives to high rollers.

Like Espinoza, MGM Resorts President Richard Sturm would love to remain in business with the fighter who helped generate a record $72-million live gate for the Pacquiao bout.

Sturm’s company will open a new NHL-ready arena in Las Vegas in May, and a Mayweather bout that could make him 50-0 would be the ultimate opening act.

Mayweather has told his closest friends he’s tired of hand and shoulder pain, and he’s repeatedly said he wants to leave boxing with his mental faculties intact.

“No one is in my shoes. My health is more important,” he said. “If you stick around anything too long, anything can happen. You can make a lot of money, but you still want to be able to talk, walk, and have a sharp mind.”

Yet, given his uninterrupted success and ability to generate the money and fame he craves, what else would he do?

“Our strategy is to remain in touch — we’ll be doing business with Mayweather Promotions — but given where he is now ... we don’t think a high-pressure approach will be successful,” Espinoza said.

“He knows that he’s in high demand, that we’d welcome him back. When the time is right, we’ll test the waters.”

What gets Mayweather’s heart racing is a challenge.

What if Miguel Cotto, who in 2012 marked up Mayweather’s face more than anyone ever has, beats Saul “Canelo” Alvarez on Nov. 21 and pushes for a rematch?

What if England’s Amir Khan wins in another impressive boxing display, and finally stops the personal attacks toward the sensitive champion?

And what if Pacquiao posts a return victory, repeats that his spring shoulder injury ruined his chance to win the first fight and offers to let Mayweather handle the entire rematch promotion without Bob Arum?

Certainly, some scenario will play out. All Mayweather has to do is kick up his feet and wait.

lance.pugmire@latimes.com

Twitter: @latimespugmire