Boxing fans' hopes for a Floyd Mayweather Jr. vs. Manny Pacquiao super fight are dwindling, and Top Rank CEO Bob Arum, Pacquiao's promoter, is openly stating that he has looked into other opponents.

"A lot of places around the world want to host a Manny Pacquiao fight," Arum said. "He's an international icon, and I have been approached by a number of people looking to host a Manny Pacquiao fight."

If the two stars can't come to terms, it is likely that Mayweather will turn to Miguel Cotto, the WBC middleweight champion, as a backup plan. But where does that leave Pacquiao?

Here are the five likeliest opponents for Pacquiao and how they rate as Mayweather replacements.

Jessie Vargas (26-0-0, 9 KO)

Vargas was the name Pacquiao's former strength trainer Alex Ariza brought up in a vicious tirade aimed at Arum recently. Ariza placed the blame for the lack of movement on a Mayweather-Pacquiao fight at Arum's doorstep, and mockingly told fans to prepare for Pacquiao-Vargas.

Ariza may not have been too far off. Vargas is a rising star, has a glossy record for Pacquiao to bust up, and like Arum said, plenty of locations in the United States and abroad would gladly host a Pacquiao fight regardless of the opponent.

Quality as Replacement: Low. This is an enormous step back from a Mayweather bout. Like Chris Algieri before him, Vargas' unbeaten record won't resonate because he's never faced an opponent of Pacquiao's caliber. He also lacks power, so fans will not view him as a threat to hurt Pacquiao, or out box him. Pacquiao and Arum would be wise to avoid this matchup if they want Pacman to remain an A-list attraction.

Ruslan Provodnikov (24-3-0, 17 KO)

Provodnikov has been rumored as a Pacquiao opponent in the past, but the fact that both are trained by Freddie Roach is a major stumbling block. Provodnikov is an entertaining fighter who would make for a great matchup with several other fighters, and while he's said he would fight Pacquiao without Roach it hardly seems that would be his first choice.

Quality as Replacement: Low. Ruslan is a fan-favorite because of his all-out, brawling style but as far as Pacquiao goes he might be easy pickings. Provodnikov knocked down Algieri twice when they met last year, and he still allowed Algieri to out box him for a victory with one eye.

Against Pacquiao, Algieri was severely outclassed and one would think that Provodnikov wouldn't fare much better with his one-dimensional approach. More entertaining than Vargas, but still a poor replacement.

Lucas Matthysse (36-3-0, 34 KO)

Matthysse may have three losses on his record, but he remains one of the hardcore fans' darlings. Like Provodnikov, Matthysse attacks with unrelenting aggression and big power. He also does it with better technical ability than the Siberian Rocky, and has feasted on bigger-name opponents. Golden Boy president Oscar De La Hoya has said he's focused on making Matthysse-Provodnikov happen, but obviously Pacquiao is a bigger fish.

Quality as Replacement: Fair. Matthysse can't hold a candle to Mayweather in terms of name recognition or in-ring skills, but he's a formidable foe that fans would respect as a threat to Pacquiao. Two of Matthysse's losses, to Devon Alexander and Zab Judah, were highly controversial defeats. He's a high-end opponent inside the ring, but there would have to be a ton of promotion to introduce him to the casual fan.

Juan Manuel Marquez (56-7-1, 40 KO)

A fifth Pacquiao-Marquez fight? If Mayweather won't face him why not? These two have never entered the ring and disappointed the fans, and it's a fight Arum loves. The only thing really standing in the way of this is Marquez's pride, and his desire to close their rivalry with his knockout win in 2012.

Quality as Replacement: Good. These guys always put on a show, Marquez is highly recognizable, and Marquez's penchant for hitting the canvas during fights could serve as a reminder of Pacquiao's electricity. He hasn't scored a knockout win since 2009, but Pacquiao definitely received a boost in excitement factor by flooring Algieri six times in a single fight.

Amir Khan (30-3-0, 19 KO)

Khan is the highest-profile fighter on the radar for Pacquiao aside from Mayweather, and has established himself as a strong contender in the welterweight division. After dominating Luis Collazo in his first 147-pound fight, Khan dismantled Top-10 welterweight Devon Alexander in December.

Khan wants Mayweather, but has said he's very interested in fighting Pacquiao as well. He also has said he believes Pacquiao presents more problems for him than Mayweather.

Quality as Replacement: Excellent. This is the SWN bet for Pacman's next fight if Mayweather doesn't happen. Khan has a huge fan base, has put his past knockout losses behind him, and looks like a different man with new trainer Virgil Hunter. Aside from Marquez, who has already beaten Pacquiao before, Khan is the likeliest man to actually knock him off.

[CBS Sports]