The 19-year-old forward has impressed in his native Portugal, scoring 15 goals and registering nine assists in just 26 league appearances last season.
He is reported to have a €120 million (£107m/$134m) release clause and had previously been strongly linked with Juventus, among other interested clubs, but Atletico appear to have won the race for the youngster’s signature, something Simeone believes is an integral part of how the club is run.
“Historically, Atletico buy young players to develop them here. Like what happened with [Jan] Oblak, [Jose] Gimenez, Lucas Hernandez when they came through from youth teams – or Griezmann,” Simeone told Fox Sports Argentina.
“We want a talented guy who can absorb our ideas. Our technical staff is already working on some situations to help to develop players.”
Simeone is dealing with a changing of the guard at Atletico, with a generation of veterans, including Diego Godin, Filipe Luis and Juanfran at the end of their contracts, but he trusts that the younger players at the club will step up to fill the void.
“It's a difficult transition we're going through, but we face it with hope. It is a challenge and today we have to face it because we are losing senior guys who have given a lot to the club.
“We are looking for Atletico to compete again as they have done so far. For seven and a half years, we were second, third, first, second. It's not easy.
“Our renovation began last year with Fernando Torres, Gabi, now Juanfran, all references, my men, those who gave me everything and who did it wonderfully well.
“At this time we were preparing Oblak, Saul, Gimenez to make them the leaders of the new squad. They are not the same as they once were – you have to try to empower them and convince them.
“If Joao Felix and others come with different characteristics than we had before, then we will have to play differently.
“In training we will see where we are going ... It is clear that this year's challenge is one of the most complex since I arrived at the club.”