The infamous former United attacker returned to Rayo last month from Eibar.
On his time with United, Bebe told the Manchester Evening News: “From day one, my relationship with Sir Alex was like what a father has with his son. He is a person who trusted me without even seeing me play. It is impossible to forget someone like that.
"I will never forget that first training session surrounded by the best players in the world. It was something unique."
But Bebe also says: "I could have used the opportunity better when I was there."