Sunderland, United Kingdom: Louis van Gaal dismissed suggestions that his side's 2-1 Premier League defeat at Sunderland on Saturday has put him under even more pressure as Manchester United manager.
An unfortunate 82nd-minute own goal by David de Gea condemned United to a loss that prevented them from closing the six-point gap that separates them from the Champions League places.
Van Gaal's position has been the subject of speculation for weeks and reports emerged last week that United have approached former Chelsea manager Jose Mourinho to replace the 64-year-old Dutchman.
But when asked if the defeat at the Stadium of Light put him under more pressure, he replied: "No. I have to do my work and I do my work to my utmost best and I cannot do more.
"I shall prepare my players against Midtjylland (in the Europa League) 100 percent and I shall do that always."
Van Gaal did admit that Champions League qualification will be "very difficult" after a shock 2-1 defeat at second-bottom Sunderland.
It leaves the 20-time English champions six points adrift of the top four with 12 games remaining after a display described by captain Wayne Rooney as "not good enough".
Anthony Martial's 10th goal of the season pulled United level before half-time, cancelling out Wahbi Khazri's opener, but Sunderland were worthy winners.
Their success will intensify the uncertainty over Van Gaal's future, with speculation mounting that former Chelsea manager Jose Mourinho is set to replace the beleaguered Dutchman at the season's end.
Van Gaal conceded that a top-four finish is the "minimum requirement" for a club of United's stature and vast resources.
But with that now looking increasingly unlikely, he said: "We needed so much the points, so in the circumstances we're in, this is very disappointing. I can't say it any other way.
"If Wayne has said it will be difficult for us to finish in the top four, then I agree with him. It's going to be very difficult now with the gap. It's still possible, but it's very difficult.
"We needed to win this game. We want to be in the top four and now it will be very difficult. That's our aim, the minimum requirement for a club like this. You can't close your eyes to this."
United can also qualify for the Champions League by winning the Europa League.
They travel to Danish side FC Midtjylland in the last 32 of the competition on Thursday and Van Gaal added: "You can say OK, that's the other way to qualify. But there are some very good sides left in that competition."
Van Gaal, who revealed that defender Matteo Darmian had suffered a dislocated left shoulder after being forced off before the interval, admitted that his players had failed to cope with Sunderland's physical approach.
- 'Big push' -
United have taken just six points from the last 21 available in away league games and won three of their last 13 top-flight matches.
"We couldn't deal with the aggressive pressure from Sunderland," Van Gaal said. "We knew the danger they posed from set-plays, but we were very bad for the first 25 minutes.
"It's not a question of being let down by the players. They want to deliver. Because they didn't deliver today (Saturday), you're disappointed and frustrated, but we're working together. We're pulling at the same strings.
"Unfortunately, Darmian is a dislocation and he's out for several weeks. We don't have any more full-backs."
The seeds of Sunderland's first victory in five games were sown in the January transfer market.
Khazri, a £9 million ($12.8 million, 11.8 million euros) buy from Bordeaux, deceived De Gea to open the scoring with a third-minute free-kick from an improbable position near the left-hand touchline.
The winner arrived when the United goalkeeper failed to deal with a header from Lamine Kone, a £5 million signing from Lorient, with Martial's attempted goal-line clearance hitting the Spaniard and going in.
"Our new boys have provided the winning goals today and that's terrific," said manager Sam Allardyce.
"It's a terrific ask of these players to get this level of performance after coming in during January. They're on their knees in the dressing room because the pace is so much quicker than they're used to playing in France.
"It was a really good performance with the right result. We've got a couple of weeks break now to get some of the injured players back.
"It's pleasing that the squad showed me it's good enough and united enough for the big push to try to get out of the trouble we're in."