Louis van Gaal admitted it was a worry to hear the first whistles of his reign, as supporters showed their dissent in Manchester United's 3-1 win over Burnley.

Fans showed their disapproval of United's wretched first-half display shortly before Chris Smalling spared his teammates further censure with his second goal of the game just before the break.

And manager Van Gaal, who accepted his side were below their best, said he did not want to lose the backing of the crowd.

"I hear the first whistles. That is a concern because we are playing for the fans," Van Gaal said in a news conference. "The fans are the most important part of the club. They keep the club living."

Van Gaal admitted he wanted to "forget" the display after relegation-threatened Burnley dominated in the first 45 minutes at Old Trafford.

"The first half was not a good performance," said Van Gaal. "Burnley was the better team. They pressed us and we could not beat the press and keep the ball. They were better and I want to give all the credit to Burnley. We score from set plays and that we train for that also.

"I was very happy we were [leading] 2-1 at half-time, because then I could reorganise my team and then the second half was a little bit better, not much but a little bit, and we could benefit the weaknesses of the opponent.

"But I said to the players when you win such matches mostly it means that we are having a good evening. We have to forget this match because it was not the best match and for the process it was not good."