From Sir Alex Ferguson, there were only supportive words. David De Gea was embarking on "a learning process", he said, and the Manchester United manager went on to recall how Peter Schmeichel had endured some difficult moments of his own during the early part of his career in England – "and Peter went on to become the greatest goalkeeper of all time".

What he did not say for certain was whether he would persist with the Spaniard or whether this was now the time to remove him from the team. But there was a clue. "Pat him on his head," he replied when asked what approach he should take. "They battered him in the second half and the referee should have protected him more . . . but welcome to English football."

The message was simple: stay calm, no knee-jerk decisions and remember why United paid Atlético Madrid £18.3m in the first place. Deep down, though, Ferguson has to be concerned. He had known there could be mistakes from the new goalkeeper but surely not of the magnitude we have seen over the past two weekends.

For long spells Ferguson's team outpassed their opponents. Ashley Young has slipped seamlessly into a fluid, attacking side and Wayne Rooney looks like a man who has found the summer break a personal affront. He is now level with Stan Pearson as the 11th highest scorer in United's history, with 148 goals. Two more and he will be level with Ruud van Nistelrooy and Paul Scholes.

But Ferguson's thoughts have to return to De Gea, particularly now that Nemanja Vidic and Rio Ferdinand have joined Rafael and Patrice Evra on the injury list. United embark on a run of eight games that include Tottenham Hotspur, Arsenal, Manchester City, Chelsea and Liverpool. Not every team will be as generous as West Bromwich Albion and there has to be a case for Anders Lindegaard to take over, even as a temporary measure.

Lindegaard's United career has been restricted to two FA Cup appearances so far but the Dane is seven years older than De Gea, has a greater penalty-box presence and, when he played in the United States in pre-season, had the trust of his team-mates and looked like a man determined to take his opportunity. There is an argument that dropping De Gea now would damage his confidence but what good will it do the 20-year-old if he keeps his place and continues in this manner? And how many points could be dropped in the process?

Ferdinand could be seen at one point clapping his hands in De Gea's direction, trying to cajole him. The keeper – sloping shoulders, wispy stubble, looking at least a couple of inches smaller than his alleged 6ft 3in – nodded back. But his body language was not convincing. Shortly afterwards a high, dropping ball came to Fábio, inside his own penalty area. The Brazilian thought about cushioning it back towards his goalkeeper but was so uncertain of his new team-mate he tried to head it clear instead. He could not get enough distance, Chris Brunt had a chance to score (he shot over) and it was that moment when we saw the first signs of the players in red starting to wonder whether the guy in goal was a danger to his own team. De Gea looked disconsolate, young, vulnerable. Jamie Redknapp talked on television afterwards of someone who "needs to grow into his kit".

At Wembley last weekend De Gea was spared a full inquisition because his team-mates were talented enough to drag themselves back from 2-0 down to win 3-2. This time he was even more fortunate but the mistake for Shane Long's goal was so wretched that all the good stuff will be forgotten. And there was good stuff. De Gea survived the second-half bombardment. There were two or three decent enough saves and he just about held his nerve, even if there was never really the sense of a man in command of his penalty area.

For now, though, what we have is a man whose presence will encourage opponents. The Premier League can be an unforgiving place and, rightly or wrongly, De Gea has already been identified as a "dodgy keeper" – someone who can be unnerved and got at. At the opposite end was a goalkeeper whom Ferguson once tipped to play for England for 10 years. Except Ben Foster lacked one key quality during his time at United: courage. That, in essence, is the first part of the learning process for De Gea – the knowledge that playing in goal for this club is not just about talent; it is a question of mentality.