Manchester City usually cope without Benjamin Mendy.
After all, they won the Premier League in record-breaking fashion in his absence last season, and in the past month they have won six of their seven games.
Pep Guardiola has simply converted Fabian Delph into a very capable deputy and even when the England man is unavailable, the City boss has been able to call on Oleksandr Zinchenko (if there's not much defending to be done) or Danilo (if there is).
There's even the option of Aymeric Laporte, who has not only played as a traditional left-back but has occasionally shuffled across from a back three to occupy the space left by Mendy's forward runs.
City, then, have plenty of options, and plainly they are usually enough to get by, whether we're talking one-off games or entire campaigns.
Yet Sunday is a different prospect as City travel to Anfield, where they have won just once since 1981. Last season, despite Guardiola's best-laid plans, they lost twice to Liverpool, conceding three goals in short bursts in both games.
Mendy has missed the last month with a bruised metatarsal and has angered his bosses with a string of off-field misdemeanours. Were it not for something of a left-back dilemma heading into the game at Anfield, it is unlikely he would be rushed back into the team; he only returned to training on Friday, after all.
Mohamed Salah has so far failed to replicate last season's top form but his enduring threat, Liverpool's general set-up in these games and the scars of last season's defeats mean Guardiola could be tempted to turn to the Frenchman.
And his decision making could be influenced by a lack of viable replacement options.
Delph would of course be the go-to guy, but he has been ruled out through injury. Laporte has been City's best centre-back so far this season but when deployed at left-back in Hoffenheim in midweek he was considerably less convincing, making a string of uncharacteristic errors. He also played on the left at Anfield in April and was caught out by Liverpool's pace.
If not Laporte, then, there is Zinchenko or Danilo. The former has generally been started only in City's most winnable games; Newcastle, West Brom, Leicester, Chelsea, Stoke and Brighton twice. Only the Stoke game was away from home, and even Chelsea let City do all the attacking; Guardiola's side enjoyed 80 per cent possession and broke a number of passing records.
The Ukrainian improved as he went along last season but he was often left out when Guardiola expected his defence to come under real scrutiny, and that will surely be the case on Sunday.
Danilo was the man for City's bigger games. The Brazilian played away at Newcastle, Crystal Palace, Burnley and Arsenal, and also faced the Gunners in the Carabao Cup final, probably his best performance while standing in as a left-back.
Yet he has only played against Oxford this season and in general he has proven an underwhelming option at left-back. Mendy he is not; Danilo can be solid at the back but adds little to the attack. That is not entirely his fault – he is a right-back after all – but that does not make him any more appealing an option for Sunday.
Guardiola and his staff are at their wit's end with Mendy. They have been left exasperated as he turned up late for training and recovery sessions, and felt he has not put in enough effort in general in recent weeks. There is a genuine feeling that they do not know what to do with him.
His situation is complicated. As much as anything, he provides as many positives on the pitch as he does negatives off it.
That is not usually enough for Guardiola, who demands complete focus from his squad, but Mendy, if motivated for the game, would bring so much to the team on Sunday.
If he is fit, Guardiola could be tempted to use him – despite everything – not just because he is a potent attacking weapon but because he would enable the City boss to try something radically different as he bids to break the club's Anfield hoodoo.
What that could be exactly is anybody's guess; with Mendy in the team this season City played completely different formations from one week to the next.
For example, against Huddersfield Guardiola played a host of central players and kept his speedy wingers on the bench, while against Newcastle he emptied the midfield – for the first time since he took charge – and played something like a four-man attack.
Without Mendy it has been the regular 4-3-3 with a string of different stand-ins, and while that will get the job done nine times out of 10, it might not be enough at Anfield.
The Frenchman is surely City's best bet – but even then, he is capable of defensive lapses that would need to be covered by his team-mates, or left unpunished by the opposition.
And even if Guardiola is able to mix up his tactics once again, he did try that without Mendy in April – bringing in Ilkay Gundogan for Raheem Sterling in a search for even more passes and control – and it back-fired anyway.
Put simply, there are no guarantees for City at Anfield. Liverpool away is the biggest test the Blues will come up against in the Premier League this season, but their task will be made somewhat easier if Mendy, for all his flaws, is available.