Southampton boss Ronald Koeman believes Memphis Depay will prove his value at Manchester United.

The PSV Eindhoven star agreed to join United last week.

Koeman commented: "It's obviously a great move for him. He's had a great season.

"He must still continue to develop. It is difficult for him because the Premier League is tough, both physically and mentally.

"He is making a big step. But remember that he is a great talent and also has a lot of speed.

"He is a very good acquisition for Manchester United."