Anzhi signed the Brazilian from Shakhtar Donetsk in January, beating off competition from leading western European teams.
Tkachenko told sports.ru: “Willian is a man who is in a category of stars, which comes immediately after Cristiano [Ronaldo] and [Lionel] Messi.
“To bring him here was our goal, our dream. It is very easy from the middle of the table to become a good team. But when you are at the top it is more difficult.”