At the start of the season, Everton felt well stocked at centre-back.
But as the campaign has gone on, as has been the case with so many facets of the playing squad, belief in those players has gradually eroded.
So as the Toffees gear up for a spell of fixtures crucial to their Premier League safety and FA Cup prospects, it remains unclear how the core of Everton's defensive structure will be compiled.
There will be no Yerry Mina for the time being at least, as he continues to recover from a high grade quadriceps tendon injury.
And it would be safe to assume that Jarrad Branthwaite is a fringe option at the moment, despite his evident promise.
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So Frank Lampard will be left with a trio of choices - Mason Holgate, Michael Keane and Ben Godfrey.
The latter of that threesome has been sidelined lately too, although images of him in training this week have been well received.
The manager confirmed that Monday's clash with Tottenham Hotspur will come too soon for Godfrey, although he can expect to be in contention for next Sunday's home tussle with Wolverhampton Wanderers.
As a result, it will likely be Keane and Holgate linking up again at the heart of the defence against Spurs.
When injuries to Godfrey and Mina made it apparent that the aforementioned duo would be the starters for a while, there was some trepidation among supporters. In the games since, they've probably performed as anticipated.
Keane has looked commanding at times, but costly errors against Southampton and Manchester City have highlighted the longstanding flaws in his game - carelessness in possession and a susceptibility to nimble forwards respectively.
Holgate has arguably been the more impressive of the two over the past month, albeit by a slender margin. Still, his dalliance in possession against Newcastle last month that led to their equaliser still sticks in the craw and the reckless challenge that saw him red-carded against Tottenham earlier in the season is also a tough one to shake.
As a pair, they are clearly fallible. Individually, they are probably Everton's third and fourth best centre-backs.
But both have a chance to play a part in saving the Toffees' season in the coming weeks.
It's why Monday's encounter feels so important for both. In terms of their short-term playing prospects and long-term futures.
Although Tottenham Hotspur have been an erratic beast this season, they can still do damage in the final third. In Son Heung-min, Harry Kane and Dejan Kulusevski they have flair, speed and potency.
Coming through the game with a clean sheet will take a momentous collective effort from the centre-back duo. Individually, they will also each be desperate to shine.
With so little between them in recent fixtures, the best performer on Monday may get the nod alongside Godfrey for matches against Wolverhampton Wanderers and Newcastle United in the Premier League before the FA Cup trip to Crystal Palace.
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Of course, there are situations where Lampard may call on all three.
The former Chelsea manager has played a back three regularly since taking charge, while Godfrey may also be tasked with doing a job at left-back. After all, Vitalii Mykolenko went off injured against Boreham Wood and Jonjoe Kenny, as steady as he has been, is clearly more comfortable on the right.
Godfrey was also short of his best earlier in the campaign, with his post-Covid fitness struggles well documented by the man himself.
Nevertheless, the blueprint laid down against Manchester City feel closest to what Lampard wants to implement at Everton - three forwards pressing high, a balanced midfield and a defence flanked by a couple of energetic full-backs.
Keane and Holgate will both feel as though they can be part of that type of setup and there have been times throughout their Everton careers when they have been. But not consistently.
Should they bolt the back door against Tottenham and restrain Kane's influence, then perhaps Lampard will persist with the pair going into the biggest week of the season rather than integrate Godfrey straight away.
But a tricky night for either may see them relegated to the bench for the foreseeable future.
With Mina's return edging closer and the potential for a reshuffle of centre-backs in the summer, that would not be an ideal place to be.
