Chelsea paid a world-record fee to sign Kepa Arrizabalaga in 2018 - but there are doubts as to whether the goalkeeper has a future at Stamford Bridge.
The Spaniard is carrying the weight of a £71.6million transfer fee, with such an outlay for a young keeper suggesting that the Blues viewed him as a David de Gea-esque signing to span a decade or more in west London.
The 25-year-old is clearly talented, but some high-profile mistakes this term have cost Chelsea at big moments - and his extraordinary outburst at coach Maurizio Sarri during last season's Carabao Cup final will not be forgotten by senior figures at the club so easily.
That is not to say that Kepa has not also bailed out a defence which is fully capable of catastrophic errors all by themselves - but Frank Lampard may feel that he cannot afford both a defence and a No.1 who are error-prone.
It would be a bitter pill for Chelsea to swallow should they admit failure and turn to another keeper: Athletic Bilbao's cantera policy - of playing only Basque players - mean any of the club's stars come at a premium; hence the Blues having to pay his release clause in full.
Having decided to make him the world's most expensive keeper, it can safely be assumed that Chelsea extensively scouted Kepa and were aware of both his strengths and weaknesses.
Scouting platform SmarterScout shows Kepa has struggled in terms of shot-stopping this season, though his passing ability from the back remains a valuable asset for the Blues.
However, it increasingly looks like Chelsea are ready to cut their losses and install a new No.1 to organise Lampard's defence.
Plenty of keepers have been linked with a move to Stamford Bridge in recent weeks - here's a run-down of how they could fit in...
Johan Cruyff said: "In my teams, the goalkeeper is the first attacker." That description fits Neuer like one of his giant gloves.
Quite simply, he is one of the most respected and talented keepers of all time. The Bayern Munich legend has won it all at club and international level, but at 34, his powers are on the wane.
While the prospect of signing Neuer initially appears a no-brainer, Chelsea fans could legitimately question whether swapping an error-prone 25-year-old for an error-prone 34-year-old makes sense.
Neuer's key strengths are his near-unparalleled distribution - both from his hands and his feet - and his command of the first third of the pitch (and sometimes further) mark him out as a unique talent.
At his age, Neuer may be tempted by the prospect of living in London and trying out the Premier League - but it would be naive to suggest it would not be a gamble on Chelsea's part.
However, his SmarterScout 2019/20 Bundesliga saving ratings are a considerable improvement on Kepa, boasting a host of ratings in the 90s compared to the Chelsea keeper's shaky efforts at set-pieces and against headers.
While Neuer has suffered foot problems over the last couple of years, his build and athleticism suggests he could play on until he is approaching his 40s.
Gianluigi Donnarumma | AC Milan
Donnarumma appears a seasoned pro given how often he has been written about in recent years, but the keeper only turned 21 in February - it is easy to forget he broke into the Milan first team at 16 years old.
It is virtually unheard of for teenaged goalkeepers to be first-team starters anywhere, let alone one of Italy's most famous clubs - but the young Italian has already been on the receiving end of the Milan fans' wrath.
In the summer of 2017, Donnarumma announced he would not be renewing his Milan contract. That led to fury among Rossoneri fans - and while the then-teenager ended up signing a new long-term deal at San Siro, the damage was done.
Bad blood exists between Donnarumma and a section of Milan fans to this day, and it would be no shock were he to seek pastures new - especially given that the club have shown no signs of returning to their glory days.
Donnarumma's current deal runs until 2021, and Milan could well cash in to fund a rebuild - especially if they miss out on Champions League football yet again.
Even with just a year left on his deal, it is likely Milan would initially demand over £70m given the precedent set by Chelsea and Liverpool for Kepa and Alisson respectively.
It is likely that fee could be negotiated down to something closer to £50m, though it would be interesting to see if Chelsea would attempt to offer Kepa as part of a swap deal.
Donnarumma also has a height advantage on Kepa: the former stands at 6'1", with the latter 6'5", perhaps going some way to explaining why Kepa struggles at set-pieces.
The Italian also boasts superior SmarterScout statistics in every department regarding saving the ball. The one area Kepa outshines Donnarumma is with the ball at his feet, however - and much depends on how highly Lampard regards a ball-playing keeper in his future team.
At 21, Donnarumma is still one of the most highly-rated young goalkeepers in world football, and - injuries permitting - has almost two decades in which to learn his trade.
Even with a huge price tag, whichever club Donnarumma ends up joining could well be getting one of the bargains of the decade.
Nick Pope | Burnley
The 27-year-old replaced Tom Heaton as the Clarets' No.1 goalkeeper and some excellent Premier League performances have seen him become an England international.
There is a belief that there could be more to come from Pope, and he could well thrive with a big move in the same way that Gary Cahill did when he signed from Bolton.
Pope is a calm, unflappable character, and while he is contracted to Burnley until 2023, he would be unlikely to cost as much as Donnarumma.
Signing Pope and keeping Kepa at the same time could spur the latter on, though it remains to be seen whether Pope would leave Burnley without a guarantee to be the No.1 keeper at his new club.
Tottenham have also been linked with Pope given Hugo Lloris' injuries and erratic form, so Chelsea may be backed into a corner regarding an early bidding war - a situation Burnley would love.
Pope's statistics for this season show a solid shot-stopper, and his impressive form in February will definitely have put him on Chelsea's radar again.
Pope is relatively young, English, Premier League-proven, and not playing for a direct rival - that makes him an exceptionally wise choice for Chelsea without costing the earth.
Verdict
Chelsea's next step will likely depend on Champions League qualification - and that is up in the air due to the coronavirus lockdown.
Assuming the season continues at some point and the Blues qualify for the Champions League, they will have their pick of keepers - and a hefty transfer budget to back it up.
However, the chances of Neuer swapping Bayern for a team in the Europa League are almost zero. With Milan struggling, Donnarumma would likely have no qualms about moving to Chelsea - but that also depends on whether the likes of PSG or Real Madrid decide they can't afford to miss out on him.
The key for Chelsea will be to take swift action. If Lampard truly feels that Kepa has had enough chances, then Donnarumma looks the ideal solution beyond signing a stop-gap No.1.
Neuer would be a dream signing for almost any club in the world, but if Chelsea are truly thinking long-term, the 21-year-old Italian could be an inspired arrival. Pope, meanwhile, would be a solid backup choice if neither were available.
