Fer has likened Holland colleague Depay to United great and current Real Madrid star Cristiano Ronaldo and believes the 21-year old, who cost the Red Devils £25million, is going to be a star at Old Trafford.
He said: "He won't be scared and that's what I like about him. He will enjoy the comparison with Ronaldo and he will be a big player.
"He's not as tall as Ronaldo but he's very talented, he's strong, he's quick, he's got the skills and he can score goals. He's a massive player and he's going to be big in Manchester.
"Of course he has to adapt to the Premier League and United are one of the biggest clubs, but I don't think it's going to be hard for him because he's a very confident player.
"Ronaldo is a bigger player than him right now because of what he's done.
"But Memphis is only 21 and if he can be as good as Ronaldo was at United he is going to be a big player. I think he can be."