"I don't shy away from anybody," Castro said at Thursday’s undercard press conference. "It has prepared me mentally and physically, knowing what I have to do and what I'm capable of in the ring. Stephen Fulton, you have to take your hat off to him. I asked for this opportunity, and I thank him and his team for it. But Saturday night, it's a different story when two great fighters step in front of each other."

Fulton (21-1, 8 KOs), also 30 and regarded as the best junior featherweight in the world before his stoppage loss to Naoya Inoue in July 2023, is seeking redemption in his official debut at featherweight. The Philadelphia native Fultons holds victories over current featherweight champions Figueroa and Angelo Leo and now aims to establish himself in the new division.

"He was the best 122-pound fighter," Castro said. "So beating Stephen Fulton would mean a lot."

Castro added that the magnitude of the fight card provides extra motivation.

"Of course, being in fights like this gives you that extra push," Castro said. "Competing against fighters like Fulton and being on the undercard of Canelo-Berlanga is a dream come true. I'm just going to go out there and give it my best."

When asked what fans can expect, Castro kept it straightforward: "A great fight."