Fulham goalkeeper Mark Schwarzer admits David De Gea must adapt quickly if he is to succeed at Manchester United.
Schwarzer has warned the former Atletico Madrid man that the Premier League is a far tougher training ground than La Liga.
He told talkSPORT: "That's the downside of playing for a club like Man United.
"He's going to have to find his form very, very quickly. It's going to be a very, very tough school for him.
"The Premier League and Spanish leagues are worlds apart in the type of football that is played."
