Now that Manny Pacquiao isn’t in Shane Mosley’s immediate future, the future Hall of Famer has turned his attention to Andre Berto.

Golden Boy Promotions, Mosley’s promoter, has begun negotiations for a welterweight title-unification bout on either Nov. 21 or Dec. 12. Mosley holds the WBA belt, Berto the WBC belt. They are rated Nos. 1 and 5 by THE RING.

Richard Schaefer said he has been in contact with HBO executives and Al Haymon, Berto’s advisor, and all sides have expressed interest in putting the fight together. Schaefer has yet to speak to Lou DiBella, Berto’s promoter.

“We’ll be crunching the numbers and presenting them to Shane in the coming days,” Schaefer said.

Schaefer said he doesn’t know where the fight would take place. He has calls into casinos in Las Vegas and is exploring the possibility of staging it at Staples Center in Los Angeles. Berto lives in Florida.

Mosley pushed hard to get Pacquiao into the ring but has announced he has given up, at least for now. Schaefer said the fighter is disappointed but ready to move on.

“Shane is the type of fighter who wants to meet the biggest fighters out there,” he said. “That’s what really gets him motivated, the mega-event. That’s what he lives for. I’m not saying Berto isn’t a big event; it absolutely is.

“It’s a title-unification fight. We just want to make the right decision, to make sure the money is right.”

And no one knows how things will play out in a deep division.

Mosley (46-5, 39 knockouts) presumably would still be in the mix in the next round of fights after Floyd Mayweather Jr. faces Juan Manuel Marquez on Sept. 19 and Pacquiao meets Miguel Cotto on Nov. 14.

“There are a lot of what-if scenarios,” Schaefer said. “Let’s assume Marquez wins. What are the best fights for him? Maybe Ricky Hatton in England. I know Ricky would like to do that. Or a rematch against Mayweather. Those are big fights.

“And if Mayweather wins, maybe Marquez goes back down in weight and is still undisputed lightweight champion. Maybe he has a rematch with Juan Diaz or maybe Erik Morales if he’s serious about coming back. Another possibility is Amir Khan.

“As far as Mayweather goes, is he supposed to wait to see what happens with Pacquiao and Cotto? Maybe he says, OK, I’ll fight Mosley instead of waiting. And what if Cotto wins? What would Mayweather do? I think Mayweather-Mosley is much bigger than Mayweather-Cotto.

“If Mayweather wins, we’ll try to get [Mayweather-Mosley] done. Pacquiao, if he wins, can fight (Edwin) Valero or whoever he wants and then fight the winner of Mosley and Mayweather. The good news is that no matter how you mix or match it, you’re going to have very big fights.”

Meanwhile, a Berto-Mosley fight would be an important opportunity for Berto (25-0, 19 KOs). The former Olympian, who represented Haiti in the 2004 Games, has been on the precipice of stardom. If he beats Mosley, which certainly won’t be easy, his career would receive a significant boost.

“Oh yeah, for Berto, it would be a huge opportunity. Absolutely,” Schaefer said.

Michael Rosenthal can be reached at [email protected]