Louis van Gaal tried his hardest to put a positive spin on the latest dull and uninspiring performance of his tenure as Manchester United manager.

Van Gaal’s team scraped into the fourth round of the FA Cup by the finest of margins, 1-0, thanks to Wayne Rooney’s stoppage-time penalty winner against Sheffield United at Old Trafford.

The Blades started the day 46 places below the 20-time English champions in the league ladder, but the Red Devils could not break down the third-tier side until Memphis Depay was clipped in the box in injury time and Jonathan Moss pointed to the spot before Rooney banged the ball past George Long.

Paul Scholes launched another attack on Van Gaal's team after the final whistle, the former United midfielder claiming the players looked "bored" during the match.

Van Gaal admitted his team’s performance was “not all right”, but he did not slate his players after the match. Instead he chose to focus on the positives, claiming he knew his team would find it hard to break down opposition as well organised and defensively minded as Sheffield United.

“I can understand (why) the manager of Sheffield United chose this kind of tactics, but they didn’t have any chances, we have kept another clean sheet and we deserved to win,” the United manager said.

“Okay it’s not good today. We did not move the ball quickly today.

“But we have won and that is the most important thing in the FA Cup, we have to be in the next round and we are there.”

United’s fans began showing their disapproval towards the end of the match when they started leaving in their thousands.

Their disappointment was understandable. They had been made to wait 69 minutes before their team had a shot on target and that was a weak effort from Matteo Darmian.

Ironic applause came from the United supporters behind the home dugout when Blades goalkeeper Long was called into action for the first time.

Boos were heard at half-time and a few came after the final whistle too as Van Gaal walked down the tunnel.

Marouane Fellaini was jeered when he was taken off in the second half. Van Gaal said the under-performing Belgian, and he himself, would have to learn to cope with the stick that came their way.

“I think a player of Manchester United has to cope with the pressure of the fans of Manchester United and also with the media pressure,” Van Gaal said.

“That is also what I expect of the manager of Manchester United. It can have an influence, but I think a player of Manchester United has to deal with that otherwise you are not a good Manchester United player.”

There was further disappointment for the United fans who are banking on a big-money transfer to turn the club’s fortunes around.

Despite admitting his squad lacks pace on the flanks, Van Gaal does not anticipate any incomings at Old Trafford in the January transfer window.

“I don’t think that we shall do business in January,” he said.

“When there is a chance to make the selection better then we shall do it but I don’t think we shall do that.”

Van Gaal complained at the start of his tenure that he was finding it hard to break down teams that defend in numbers.

When asked why he had failed to rectify that problem 18 months into his reign, Van Gaal said: “Because it is the most difficult situation in the match.

“It is like that and I have said also in the (summer) transfer period that we need creative players with speed and we don’t have that too much.

"Juan Mata is playing the right side and he is doing fantastically well because he always has a big contribution for our team, but he is not a right winger in the profile I have.

“But it is not so easy to purchase players who are better than Mata because even though he is in a different profile, he is a very good right winger in our way of playing.”