Floyd Mayweather's opponent list pared

The identity of welterweight titleholder Floyd Mayweather Jr.'s next opponent remains unknown, but you can scratch Robert Guerrero, who had been one of the leading candidates, off the list.

"It's not going to be Guerrero," Golden Boy promoter Richard Schaefer told ESPN.com on Wednesday night.

Schaefer declined to comment any further.

Mayweather plans to fight May 5 at the MGM Grand in Las Vegas before he begins an 87-day jail sentence at the Clark County Detention Center in Las Vegas on June 1.

His jail term was supposed to begin last Friday, but his lawyer, Richard Wright, successfully argued that it should be delayed so Mayweather could honor a commitment to a May 5 fight at the MGM Grand, which would pump an estimated $100 million into the ailing Las Vegas economy. Mayweather pleaded guilty last month to a reduced battery domestic-violence charge and no contest to two harassment charges, stemming from a hair-pulling, punching and arm-twisting argument with his ex-girlfriend in front of two of their children.

Besides Guerrero, another opponent Golden Boy has mentioned as a possible opponent for Mayweather is junior middleweight titleholder Saul "Canelo" Alvarez (39-0-1, 29 KOs). Miguel Cotto (37-2, 30 KOs), also a junior middleweight titlist, potentially could be in the mix as well.

The one fighter who looms over all of them is fellow welterweight titleholder Manny Pacquiao, whom Mayweather called out Tuesday on Twitter, although that mega fight, which has been heavily anticipated for more than two years, remains a long shot. The camps continue to go back and forth with rhetoric but are not, at least that is publicly known, negotiating the fight. They have instead bickered about the date and site in the media.

Guerrero (29-1-1, 18 KOs), a former featherweight and junior lightweight titlist (and interim lightweight titleholder) emerged as a candidate because he has relentlessly pursued the fight through the efforts of publicist Mario Serrano and because he is promoted by Golden Boy, which has served as Mayweather's promoter for his last five bouts even though they do not have a formal promotional contract.

However, Guerrero would have to jump up two weight classes and is coming off rotator cuff surgery. The suggestion that he might land a fight with Mayweather (42-0, 26 KOs) despite the size difference, the question marks about his injury and his lack of big-fight experience was met with wide disappointment by boxing fans.

Guerrero's team declined comment.

Dan Rafael covers boxing for ESPN.com. Follow him on Twitter.