Former five division world champion Floyd Mayweather Jr. believes a welterweight showdown between Terence Crawford (32-0, 23 KOs) vs. Errol Spence (23-0, 20 KOs) will eventually become the biggest fight in the sport.

From the moment Crawford announced his move to 147-pounds, fans began clamoring to see him and Spence in the ring.

"Honestly speaking, I think soon the biggest fight that's going to be in boxing is Terence Crawford and Errol Spence. That's going to be a huge fight I think in boxing. In the future [it's going to be pay-per-view worthy], in the future [it will be pay-per-view] but not right now. I would pay to see it," Mayweather told Fighthype.com.

While Crawford's handlers view Keith Thurman as a tougher contest, Mayweather disagrees and says Spence is without question the tougher task.

Last year, Spence traveled over to the UK and picked up a knockout victory over Kell Brook to capture the IBF championship.

He is scheduled to return in a Showtime televised fight on June 16th in his hometown of Dallas, Texas. The opponent is still slated to be undefeated mandatory challenger Carlos Ocampo of Mexico.

Crawford had his own level of success in 2017. He knocked out Julius Indongo to unify the entire junior welterweight division as he brought together the IBF, WBC, WBO, WBA world titles. And prior to that win he secured a stoppage victory over Olympic gold medal winner Felix Diaz.

Following his capture of the belts, Crawford announced his move to the welterweight class and vacated all four titles.

Crawford was immediately made the mandatory challenger by the World Boxing Organization. He was scheduled to fight WBO welterweight champion Jeff Horn on April 14th at the T-Mobile Arena in Las Vegas.

But the contest was postponed after Crawford suffered a hand injury in training camp.

Now the contest will take place on June 9th, at Las Vegas' MGM Grand.