The junior coach of Lucas Hernandez was delighted for the defender after his performance for Atletico Madrid against Real Madrid.
Lucas was outstanding in Saturday's stalemate at the Metropolitano.
Santi Expósito, who worked for Atletico but is now coaching at Real Madrid, told AS: "I'm very happy for him, I'm not surprised by his level.
"(At 11 years old) He came a few days after the season started and he impressed us. In that team we had Rodri, who is now with Villarreal, and Rober, who last year debuted with Cholo (Simeone).
"I do not know how much Lucas would be worth in the market right now, but he has a tremendous present and a future. The derby was not chance or something timely. I do not know where his ceiling will be. He will arrive wherever he wants, because he is competitive and has plenty of talent."