Denayer left City on a permanent deal in the summer, and will return to the Etihad tonight with his new club Lyon.
He has played twice for the French side so far this season, and Wilmots believes City will regret letting him go.
Wilmots, who gave Denayer his national debut, told L'Equipe, “His main quality is his speed. He has the power and technique and can still improve his game defensive wise, but is not bad so far.
“He has a good jump and even though he will not be Virgil Van Dijk, because of his size. For the rest, it has it all.
“This is the new Kompany, without the charisma."