Spence, who holds three welterweight titles, and Crawford, owner of one 147-pound belt, are closing in on a deal for an October fight in Las Vegas for the undisputed welterweight championship, sources tell ESPN.

The boxers are still in negotiations and there is no agreement yet for the fight, which would be presented by PBC on pay-per-view, sources said.

"I'm free to do whatever I want," Crawford, 34, told ESPN in late April. "There's nothing standing in the way from us fighting. There's no promotion company that's blocking it, there's no wrong side of the street, there's no nothing. Let's see who the best welterweight in the world is."

Crawford, ESPN's No. 1 pound-for-pound boxer, parted ways with his longtime promoter, Top Rank, after a 10th-round TKO of Shawn Porter in November. PBC, with which Spence is aligned, rarely does business with other promoters. Now that Crawford is a free agent, the path is clear to make the superfight.

The sport's inability to deliver the fight has been a source of frustration among fans for years. But Crawford believes the matchup is "definitely ... bigger now."

Spence, ESPN's No. 3 pound-for-pound boxer, returned from surgery to repair a detached retina to score a 10th-round TKO of Yordenis Ugas in April. The 32-year-old from Desoto, Texas, was set to fight the legendary Manny Pacquiao in August but withdrew from the bout when it was discovered that he required immediate surgery.