Chelsea transfers adviser Piet de Visser has revealed their interest in SC Heerenveen midfielder Daley Sinkgraven.

The Heerenveen youngster has reportedly been on Manchester United's radar after his performances caught the eye of Louis van Gaal.

De Visser told Voetbal International: "On Daley Sinkgraven, I find it very difficult to say anything because I've agreed with Chelsea that I will not speak about the talents that are on our list.

"I follow him and that goes beyond watching a game from time to time."

He added: "I look for five things, technique, anticipation, passing, dribbling, vision. Can he read the game, see the right solution?

"Physically, has he speed, power, endurance and mental dexterity? He absolutely has to have the will to win."