The 71-year-old spent seven years in charge of Portugal, a spell that took in two World Cups, three European Championships and a Confederations Cup, and it was Santos who first handed Bernardo Silva his international debut, against Cape Verde back in 2015.
Speaking to AS, and asking, respectfully, to steer clear of Portugal's own World Cup campaign this summer, Santos reflected instead on the midfielder's move to the Bernabeu.
How would you define Bernardo Silva?
"Everyone already knows him as a footballer, he has immense quality and sees the game like very few players in the world do. His bar as a player is so high that it's difficult to say he's on the same level as a person, but in his case it's true. He's attentive, polite, kind and always has a smile on his face.
"On a personal and human level, he's one of the best footballers I've known in my entire career. Madrid have signed a phenomenon in every sense."
What makes him a different kind of player?
"His intelligence. He's an extremely strong player technically and extraordinary tactically. He understands the game very well and knows how to read every situation on the pitch perfectly. He always knows what to do with the ball and how to position himself when he doesn't have it. I've used him as an interior midfielder, as an attacking midfielder and even as a winger, and his performances have been excellent in every position."
Is he still at his best at 31?
"From what I've seen this season at City, I'd say yes. I know him perfectly and I'm convinced he still has very good years ahead of him. He remains at the peak of his career and he's going to prove it. For me he's still one of the best in the world. I think Real Madrid have got it right with this signing and he's going to contribute a great deal to his team."
How might he fit alongside Mbappe, Vinicius and Bellingham?
"Great players know how to adapt to every situation and circumstance of a match. He's very good at that and won't have any problem playing wherever he's asked. I'm sure Mourinho already has a role in mind for him and Bernardo will fulfil it perfectly."
Bernardo Silva joined Real Madrid this summer on a two-year deal, ending nine years at Manchester City.