Andre Onana and Man Utd's big fear about history following dreadful mistake

With De Gea toiling as United lost to City on a sunny day at Wembley, however, Ten Hag then opted to be ruthless and wield the axe.

The 32-year-old was shown the door, without even having a chance to say goodbye to fans. Out with the old and in with the new.

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Ten Hag then opted to sign Andre Onana from Inter Milan, having previously managed the Cameroon international at Ajax in the Netherlands.

Fast-forward to now, however, and the shot-stopper is already under pressure having struggled to make his mark.

The stats make for grim reading. Onana has already shipped 14 goals from just six matches this season, with United looking a shadow of the promising team they started to resemble last term.

The Red Devils are vulnerable and the sharks are circling, sensing blood with each and every match.

On Wednesday night, in the cauldron of the Allianz Arena, Onana made a huge mistake by allowing a shot from Leroy Sane to squirm under his body.

Onana should have saved it. De Gea, probably, would have.

But the 27-year-old's rocky start to life in his new surroundings stooped to a new low, something he admitted after the match.

"Their first shot on target, I made a mistake, so the team went down because of that mistake," he said.

He added: "I have a lot to prove. My start in Manchester has not been good or how I want. The way I played today was one of my worst games.

"It's difficult as we are a big club who wants to win everything. It was a good opportunity to bounce back after the situation we are facing - it's a tough time, we have to be together and continue to work hard."

Onana was brilliant for Inter Milan last season.

He was particularly impressive in the Champions League final defeat to Manchester City, even earning praise from Pep Guardiola.

But United can now be forgiven for fearing history is repeating itself.

Great goalkeepers aren't easy to replace. And make no mistake about it, De Gea was once great.

Just ask Sir Alex Ferguson and how he struggled to replace Peter Schmeichel when the Denmark international departed in 1999.

United had hoped the icon would remain at Old Trafford and continue to play a big role in their success.

Schmeichel stunned the club by asking to leave, however, and went to Sporting Lisbon because the slower pace of Portuguese football appealed to him.

Mark Bosnich was immediately signed by United and given the chance to stake his claim for the No 1 jersey, having impressed for Aston Villa.

But the Australian was later described as a 'terrible professional' by Ferguson and he was flogged to Chelsea just two years later.

The less said about Massimo Taibi, the better. The Italian made just four appearances for United and a dreadful mistake against Southampton still does the rounds now, many years later.

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Fabien Barthez, for a while, looked as though he'd be the one to finally replace Schmeichel.

Despite being a World Cup winner with France in 1999, however, he was never able to live up to expectations.

Roy Carroll and Tim Howard both then competed for the No 1 jersey for a couple of seasons.

However, both men made mistakes and never looked good enough to be between the sticks for a trophy-chasing juggernaut.

It wasn't until Edwin van der Sar signed for United in 2005 that they finally struck gold, with the Dutchman etching his name into Old Trafford folklore.

Now, United fear a repeat. What if they got the wrong man?

That's something Onana will have to overcome. History can't repeat itself - not with the Red Devils already alarmingly off the pace.