Washington: )WBA welterweight champion Shane Mosley feared he would never get to fight fellow American Floyd Mayweather, until "destiny" played its part.

The pair will clash in Las Vegas on May 1 in a fight Mosley (46-5, 39 knockouts) said was the biggest of his illustrious career.

"It's a fight the world wants to see," he said on Tuesday during a teleconference with reporters.

After Mayweather (40-0, 25 KOs) defeated Juan Manuel Marquez last September, and Manny Pacquiao of the Philippines defeated WBO welterweight champion Miguel Cotto, it seemed certain that Mayweather and Pacquiao would clash this year.

But negotiations collapsed over Mayweather's demands for random drug testing, and Mosley stepped in to take the Filipino's place.

"I have to be honest, I thought they were going to be able to avoid me," Mosley admitted in a separate call with Reuters.

"I thought they would be able to fight each other and retire. But this is the fight that had to happen. This is a fight of destiny."