Chelsea boss Roberto di Matteo has welcomed their deal for Werder Bremen winger Marko Marin.
Di Matteo has no doubts he will be a major success for the west London club next season.
He said: "He's an exciting player, a young German international. He's a very good player, technically. Skilful. He will add some qualities to this team.
"I tend to give my recommendation, but ultimately the club decides who they want to buy."