MIDDLESBROUGH have completed the signing of defensive midfielder Marten de Roon.

The 25-year-old has signed a four-year deal after Boro agreed to pay a fee believed to be worth around £11.75m to Atalanta.

De Roon impressed during his one season in Italy, having started out at Sparta Rotterdam and then Heerenveen.

De Roon admitted he was looking forward to the challenges ahead.

He posted on his official Twitter page: "Really happy with my transfer to Middlesbrough! Let's make a good season in the Premier League. Come on The Boro!"

He follows Viktor Fischer and Bernardo Espinosa to the Riverside Stadium after their moves from Ajax and Sporting Gijon.