It took six years to finally fill Peter Schmeichel's gloves after the Dane left in 1999, when Sir Alex Ferguson brought in Edwin van der Sar from Fulham.
But during that period the Scot went through Mark Bosnich, Massimo Taibi, Ricardo, Fabien Barthez, Roy Carroll and Tim Howard and all failed to convince the 69-year-old - some in frankly laughable attempts.
Spring in the step: De Gea is poised to become the next Manchester United No.1
With the Dutchman retiring after the Champions League final, Ferguson faces a similar conundrum only this time he has opted to spend a hefty ?17.8million on David de Gea from Atletico Madrid.
But is he the long term successor to Van der Sar or just another Taibi? In terms of raw ability the 20-year-old has it all. He possesses sharp reflexes, good handling skills, stands up well and is brave.
But for the money United have spent you are going to want at least some big-match experience to back it up and he hardly has any.
He may have won the Europa League, but just one full season in La Liga and a single appearance in the group stage of the Champions League is not solid foundations for someone who can do it at the very highest level - he hasn't even been capped by Spain yet.
Keeper's ball! De Gea (left) comes to punch clear in a league game against Celta Vigo last year
However, plenty of 20-year-old keepers display the attributes that De Gea does but very few can also show the maturity that the Spaniard has in his game.
He is seen as the natural successor to the immovable object in the Spain team's goal, Iker Casillas. Despite his obvious potential at 20, even Casillas was typically error-prone for a young stopper and De Gea looks a better prospect at the same age.
United scouts would have done their homework, Ferguson would have seen the keeper in action, but there are three key factors that no amount of scouting, data-analysing or talks can unearth.
Out in the cold. De Gea feels the temperature in a Europa League match at Bayer Leverkusen earlier in the season
Major success: De Gea celebrates winning the Europa League last year, a day after beating Fulham in the final
The first is how he settles in England. It's all very well producing your best at your hometown club with the comforts of familiar surroundings, but many a player has shone in another domestic league before bombing in the Premier League just because of a failure to adapt to a new lifestyle.
The second is the toughness of the Premier League. That's not to say England's top-flight is better than Spain's (that is another debate), but it is different.
On the up: Ferguson is convinced of De Gea's abilities after just one full season
It's all very well pulling off impressive saves from the likes of Messi and Ronaldo (which he does enough already) but it will be interesting to see he how he can cope with tactics like Rory Delap's throw-in or a high Paul Robinson free-kick into the box - it's not something you see often in Spain and the Premier League is a different animal.
The final factor is how he deals with the pressure of playing for Manchester United. Atletico Madrid are a big club but United they are not. Many experienced keepers, some in the third paragraph, have taken the No 1 jersey and failed to deliver.
At a younger age and making a big step up, De Gea will be under immediate pressure to justify his price-tag, whether that is fair or not.
Statisticians have already identified a weakness in him, with the stopper conceding more goals to shots from outside the area than any goalkeeper in La Liga this season with 11 - it's all valuable information to opposing teams.
Regardless of the price, the decision to make such a raw unproven talent No 1 is a huge gamble for Ferguson.
Optimists will point towards the big success of Javier Hernandez this term as proof that Fergie can still sniff out a good deal, but for every Chicharito there is a Bebe
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Explore more:People: Alex Ferguson, Paul Robinson, Mark Bosnich, Edwin Van Der Sar Places: Spain, United Kingdom