Atletico Madrid midfielder Saul claims that he had his boots and food stolen during his time in the youth academy of fierce rivals Real Madrid.
Saul spent time on the books at the Santiago Bernabeu before switching to Atletico and climbing through the ranks to become a member of the first team.
The 21-year-old says he does not regret his time at Real and learned a lot during his formative years, but stated he endured problems off the pitch.
"I'm not hurt by what happened because it was a good experience in that I learned a lot of things, I matured a lot as a person," Saul told El Mundo ahead of Saturday's contest between the sides at the Santiago Bernabeu.
"A lot of things happened off the field. The sporting side went well but some things happened which shouldn't happen to a kid of 11, 12 years of age.
"I had my boots stolen, my food, I was punished for something I didn't do and I wasn't allowed at the training ground in Valdebebas for two weeks.
"Someone wrote a letter, signing it with my name and sent it to the coach. I said that the letter wasn't from me because I had nothing to do with it."
Saul, who has made 19 appearances for an Atleti side that are second in La Liga this season, says the values instilled in him at Atleti are "a way of life".
"Atleti is not just about the club crest, an emblem - it's all about the club's values, a way of living life. Humility, hard work, sacrifice, unity, the importance and strength of the team," he added.