Shawn Porter is still unsure if the super showdown between Manny Pacquiao and Floyd Mayweather Jr. will happen in May. But if it does, the former world welterweight champion believes Pacquiao could hand Mayweather the first defeat of his illustrious career.

Porter is familiar with Pacquiao, having sparred with the Filipino boxing icon before. The former International Boxing Federation welterweight champion told BoxingScene that Pacquiao will defeat Mayweather because his former sparring mate is more versatile than the unbeaten champion.

"For me I think that Manny is the favorite because he is a little more versatile than Floyd at this point in his career," said Porter, who wants a shot against either Pacquiao or Mayweather. "I think Floyd likes to use his defense and counter punch while Manny does a little bit of everything and does it from a southpaw position. That is a great fight."

While Porter is convinced Pacquiao will hand Mayweather his first loss, former world champion Brandon Rios, who is also familiar with the Pacquiao's fight style, thinks otherwise.

Rios, who took a lopsided unanimous decision loss to Pacquiao in their nontitle fight in November 2013 in Macau, believes Mayweather, who holds an unblemished 47-0 record, will be too much for the reigning World Boxing Organization welterweight champion.

Rios thinks Pacquiao has lost a step and does not have the killer instinct that he had before. The 28-year-old California native also added that Pacquiao will have a difficult time dealing with Mayweather's vaunted defense.

"It feels wrong for me to say this but I think Floyd beats Manny Pacquiao," Rios said in an interview with On The Ropes Boxing Radio. "Floyd is just a very defensive fighter, he's got so many skills, he's been in so many positions and he does have that skill. I do believe that Floyd beats him."

Rios added, though, that he cannot see Mayweather winning by knockout against Pacquiao because the reigning pound-for-pound king will not engage in a slugfest with his biggest rival, knowing that his opponent is known for his punching power.

"I think decision, I don't see anything else. I think it would just be a decision because Floyd is too smart to do anything else," Rios said. "He's not gonna take a risk and try to get hurt himself."

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