Values joined Boro on a free in early July following a disappointing spell at Manchester United and the 34-year-old admits it was a shock for him to hear that a man with such close ties to the Santiago Bernabeu was eager to work with him.
"I want to thank Aitor Karanka for saying such nice things about me. He says having me here is a privilege but the privilege is all mine," a humble Valdes told Sky Sports News HQ.
"Playing with a newly promoted club means I have a different objective in my career but I still always want to go out there and win games. I am grateful to Karanka for the chance.
"He had been texting me for a while. He sent me a message after my knee injury and we have kept in touch since.
"It was a surprise because he is a Real Madrid legend - there is obviously a fierce rivalry there."