Louis van Gaal needs to be "very careful" with new signing Memphis Depay to ensure he shines at Manchester United, according to former Netherlands international Pierre van Hooijdonk.

Depay, 21, completed his transfer to United from PSV Eindhoven earlier this month, for a reported fee of £25 million, after scoring 22 Eredivisie goals last season.

Van Hooijdonk, who played in England for Nottingham Forest, believes the attacker has the potential to be an Old Trafford great, but only if he is provided with the right environment to thrive.

He said in the Sunday People: "I don't know yet how Depay will fit in and in which position, but when you sign a forward player you have to be very careful.