MANILA, Philippines – Robert Guerrero is already being installed as a massive underdog against unbeaten American Floyd Mayweather Jr., but “The Ghost” is confident that he knows the key to defeating the pound-for-pound king.

Guerrero has been calling out Mayweather for a couple of years now and will finally get his shot at “Money” on May 4 in Las Vegas.

“I know it would come. Working hard and putting up the fights I’ve been putting up,” he said in an interview on KNBR radio, as quoted by Sports Radio Interviews.

“The Ghost,” who totes a a 31-1-1 win-loss-draw record, believes he has what it takes to beat Mayweather because of his versatility.

“I’m versatile in the ring. You look at all my films and my previous fights, and I never fight the same style,” he said.

“I come in different. I can fight on the inside or outside, I can be a boxer or a puncher, I can just be a boxer, a slugger. I’m able to change it up and be versatile in the ring,” Guerrero said. “It makes it much more challenging.”

Guerrero also pointed out that he is a southpaw who is “not scared to fight.”

“(I’m) not scared to throw punches and get in there and take a shot. That’s what Floyd respects too in the ring. It’s going to be a dogfight,” he said.

When informed that Mayweather was a 12-1 favorite against him, Guerrero said he expects the odds to change as the fight draws nearer.

“People start seeing what’s going on in the camps, how fighters are looking, how we’re training, how everything is going, then the odds start to change,” he said. “They’re going to start changing here pretty soon.”

Guerrero is coming off an impressive unanimous decision victory over Andre Berto last November, a fight that saw him drop Berto once in the first two rounds.

Mayweather, meanwhile, will fight for the first time since outpointing Puerto Rican star Miguel Cotto in an exciting fight last May 2012.