Charlie Austin’s headed goal, seven minutes after making his Southampton debut from the subs’ bench, was a new low point in United’s miserable season.
Van Gaal’s side managed just one shot on target as they failed to score at Old Trafford for the seventh time in a campaign which has brought them their lowest ever points tally at this stage of a Premier League season.
They have won just three of their last 13 games and are five points away from a top-four place.
The damning statistics keep stacking up and van Gaal may not be able to take many more blows.
The United supporters have not enjoyed his unambitious style of football and his pay-masters are increasingly coming round to that way of thinking.
Winning games can paper over a lot of cracks but there was no scraped victory to bale van Gaal out this time and he offered no defence to the boos and jeers from the supporters that greeted him as he walked the gauntlet down the touchline back to the dressing room after the final whistle.
“I agree with them, so it doesn’t have any impact,” he claimed.
“They have also knowledge of football, of entertaining football, and you have to play football to entertain the fans.
“Today, I don’t think we have entertained the fans, so they can be very angry. But when we have won, then they were not so angry anymore, and that’s football. But now we have lost in the last minute...
“I’m very disappointed I cannot reach the expectations of the fans. They have — or they had — great expectations of me, and I cannot fulfil them, so I am very frustrated.”
Van Gaal, 64, has won league titles in Spain, Germany and the Netherlands and is also a Champions League-winning coach but is unable to pinpoint the defining reason why United continue to slip further from the peak they last hit as champions under Alex Ferguson — who must have found this painful viewing from the directors’ box — in 2013.
“You cannot say it is that aspect or that aspect, because there are different aspects that play a role and we are not very lucky with our injuries, so that’s also a problem,” he added.
“But, nevertheless, we had to win today, and we could have won today, but it is not happening.”
“For the fans it was a poor performance, because you have seen two teams who were very busy with the tactics, but they don’t create many chances, and that’s why it was a poor match.
“But we could have won this match, and I had the feeling we could do that also in the final minutes.”
It’s hard to see how, with the best United could have hoped for a barely deserved point from an injury-time chance which fell to substitute Adnan Januzaj.
Had he found the bottom corner instead of shooting wide it would have been some comeback following his return from an unhappy loan spell at Borussia Dortmund.
Instead, Januzaj’s biggest impact was in giving away the free-kick which James Ward-Prowse swung onto the head of Austin to underline why he will prove such a bargain buy from QPR, as he secured a third successive league win for Ronald Koeman’s side.
“For any striker, moving in January is tough and to get that first goal is very important so I’m just delighted to get it so early on,” said Austin.
The 26-year-old is a natural goalscorer who proved last season that he can do it in the top flight. United are desperate for someone like him, although even Austin might find it difficult to score in this team which on Saturday didn’t make a chance worthy of the name.
The only consolation for many United supporters is that they may not have to watch much more of this under van Gaal if the club’s hierarchy also decides enough is enough.
De Gea 6; Darmian 7 (McNair 60, 6), Smalling 6, Blind 6, Borthwick-Jackson 6 (Januzaj 86); Schneiderlin 5, Fellaini 5 (Mata ht, 7); Lingard 4, Herrera 5, Martial 4; Rooney 5. Substitutes: Romero, Depay, Varela, Pereira.
Forster 6; van Dijk 8, Fonte 8, Bertrand 8; Soares 7, Wanyama 8, Clasie 7 (Romeu 67), Targett 7; Tadic 7 (Ward-Prowse 67), Mane 7 (Austin 79); Long 8. Substitutes: Stekelenburg, Yoshida, Martina, Juanmi.
Michael Jones 8
Former Manchester United chief executive David Gill has called for calm amid more speculation over the future of manager Louis van Gaal in what he admits is a season of “under-achievement”.
Gill, who remains a non-executive director of United, says he went to the cinema instead of watching Match of the Day following the club’s 1-0 home defeat by Southampton on Saturday, which left the Red Devils five points adrift of fourth-placed Tottenham.
Speaking on BBC Radio 5 Live, Gill said: “Clearly we all hoped the results would have been better and everyone is disappointed with that. It’s been a season of under-achievement.
“But I know that everyone, from the owners and Louis van Gaal and his team, is working extremely hard to turn that around. It’s not easy but we have to stick together.
“What you’ve got to do is stick to what you know is right to turn it around and don’t get too distracted.”
United were booed by their fans and Van Gaal admitted it was the worst reaction he has so far experienced in the job.
The FA vice-chairman, who declined to comment on a report that former Chelsea boss Jose Mourinho has written to United to state his case to become the club’s next manager, does not believe Van Gaal is finding the job more difficult than he imagined.