Chelsea boss Jose Mourinho believes that Louis van Gaal needs time to adapt to life at Manchester United.
The Red Devils are currently third in the Premier League, but Van Gaal has come in for criticism for his tactics this term.
However, Mourinho has likened the Dutchman's arrival to that of a foreign player and thinks that his former boss will eventually succeed at Old Trafford.
The Portuguese told Sky Sports News: "He's a fantastic coach, and it's easy for me to say because I know him so well, he's a fantastic person as well. In the same way a player needs to adapt, he needs to understand the performance in England, and it is a bit the same.
"I understand that it will take time for Louis to build a team to win titles again. He can still do that with the FA Cup and they can finish in the top four and get back in the top four.
"I was coming from a few years with Mr (Bobby) Robson, and it was a learning process because he had a complete different philosophy in terms of the model of play. It was an important period of my career."
Mourinho worked under Van Gaal during his time on the coaching staff at Barcelona.