Manchester United manager Louis van Gaal believes that all the players he bought since his arrival this summer will take at least a year to settle at the club.

Of all the arrivals, British record signing Angel di Maria has been under the scanner off late as he struggles to replicate the blistering form he displayed during the first couple of months since his arrival. The former Real Madrid winger has struggled in recent months and has failed to score a goal in the Premier League since the beginning of October.

During United's clash against Sunderland last weekend, the Argentine international, who started the game was substituted at half-time and the manager admitted that it was because Di Maria "was not in the game".

Another summer arrival who has struggled to impress is Radamel Falcao. The Colombian striker, who arrived on-loan from Ligue 1 club AS Monaco has failed to make an impression on the manager, which in turn has jeopardised the agreement with the club to make his deal permanent at the end of the current season depending on his performances for United.

However, the Dutch manager has defended all the new players and admits that he would have been more shocked if the players had hit the ground immediately after their arrival.

"It counts for all the players. The first season is always difficult. You can see it with every player we have bought, Shaw, Blind, Herrera, Rojo, Falcao and Di Maria," Van Gaal said, as quoted by the Manchester Evening News.

"It is not a big surprise. It would be more a surprise if they adapted very quickly. I have experienced this in the Netherlands, Spain and Germany. It has been the same experience with other players," the Red Devils manager explained.

"We have to give them time. It is the same for all the player. We wait and see."

He feels that each player takes their own time to adapt to a new league and the different cultures at every club, but feels that it generally takes a year for them to finally become part of the club and its philosophy.

"How players adapt is dependable on the individual. You also have to manage so many different aspects. You have to manage things in the match and cultures off the field."

"You cannot give a general answer to how long it takes for a player to adapt...but the general answer is one year!" Van Gaal concluded.