Zayas, 23, is scheduled to defend his WBA and WBO junior middleweight titles against Ennis on June 27 at Brooklyn’s Barclays Center in by far the most challenging fight of his young career.

The Puerto Rican's talent is undeniable but a key question going into the fight is whether he has enough seasoning to take that sort of leap. The 28-year-old Ennis (35-0, 31 KOs) is supremely gifted and more experienced.

“That’s a tough fight,” Crawford told Jai McAllister earlier this month, "especially for Xander at this point in his career. He’s gonna do real well in that fight, but I just think right now, it’s a little bit too early for him.”

Zayas (23-0, 13 KOs) has been in big fights. Last July, he won the WBO belt – his first world title – thanks to a dominant points win over Jorge Garcia Perez. Six months later, he knocked off Abass Baraou by a split decision to add the WBA title and become the sport's youngest unified world champion.

Still, Ennis (35-0, 31 KOs, 1 NC) does some things in the ring that you simply can’t teach.

The Philadelphia star gave up his unified welterweight championship when he officially moved up in weight last year. For his 154-pound debut, Uisma Lima was served up as a sacrificial lamb, getting stopped in the first round.

Crawford, who held the WBA 154-pound title and was once considered the division’s top dog, admires Zayas for trying his luck against someone as good as Ennis. Although the oddsmakers have made him a significant underdog, Crawford believes anything is possible provided he maintains the self-belief that got him to this position.

“It shows his heart and the confidence that he has in himself,” Crawford said. “He’s ready to go make history.”