The Chelsea wide man has expressed his sadness at the impending departure of Diego Costa as well.
Matic joined the Red Devils in a £40m move earlier this summer while Costa has been told he is surplus to requirements at Stamford Bridge but is yet to leave.
Alvaro Morata has been brought in to replace Costa and Willian is confident he can step up to fill the void soon to be left by the madcap Brazilian forward.
And he has a lot to live up to with his £60m price tag weighing heavy on the Spaniard's shoulders.
Willian told Goal: "Everyone knows about Diego Costa's quality, the striker he is, and I am sad because he is leaving.
“He has not yet go to any club, but Morata, who has arrived, has quality and knows how to score goals too.
“Me and the other players are here to give all the support to our new players, for they can earn at Chelsea what they have been doing in their previous clubs.