We take a look at some of the potential issues facing Jurgen Klopp following Liverpool's 1-0 loss to Napoli in the Champions League on Wednesday night.
Lorenzo Insigne's late goal consigned Liverpool to defeat at the Stadio San Paolo, meaning they go into their Super Sunday showdown with Manchester City on a three-game winless streak.
From the Naby Keita injury scare to Liverpool's defensive vulnerability, here are the headaches facing Klopp.
Keita injury blow
The consensus among Liverpool supporters after their 1-1 draw with Chelsea on Saturday was that it was time to replace Jordan Henderson with Keita in the starting line-up. They got their wish on Wednesday night, but having been stretchered off with an apparent back injury early on, it now seems Keita is facing more time on the sidelines.
In truth, his performance up until then hinted at why has found himself on the bench recently. Keita committed a clumsy foul on Napoli defender Nikola Maksimovic after just three minutes, and he went on to lose possession five times in only around a quarter of an hour on the pitch - at one point almost gifting a scoring chance to Napoli striker Arkadiusz Milik.
Keita is still acclimatising to his new surroundings following his summer arrival from RB Leipzig, but his absence is nonetheless a blow to Klopp ahead of City's visit to Anfield on Sunday. The sooner he recovers, the sooner he can get up to speed with his new team-mates.
Fatigue an issue?
Keita for Henderson was the only change to the Liverpool starting line-up from the pulsating 1-1 draw with Chelsea at Stamford Bridge at the weekend, so it was hardly surprising that there were signs of fatigue against Napoli.
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Liverpool coped adequately in the first half, enjoying a roughly even share of possession and matching Napoli for shots on goal, but the heavy legs showed as they were overrun in the second half. The issues were most apparent in midfield, where James Milner, Henderson and Georginio Wijnaldum were unable to keep up with the rampant hosts.
Klopp admitted Liverpool had lost the midfield battle afterwards, but having used largely the same personnel during a run of four games in 12 days, Klopp's midfielders were not the only ones who seemed to be feeling the effects. They now need to summon the energy to overcome Manchester City, who will have benefitted from an extra day's rest having played their Champions League game on Tuesday.
Salah questions linger
Mohamed Salah's recent form was defended by Jamie Carragher on Monday Night Football, with the Sky Sports pundit pointing to the underlying data which indicates he is still getting into the right positions, but following his early withdrawal against Chelsea on Saturday, this was another display to raise questions.
The Egyptian did not get great service, in fairness, but when opportunities did come his way he was unable to hit the target, firing both of his efforts wide. He was also guilty of wasting one of Liverpool's best openings in the first half, when his cut-back was easily cut-out by David Ospina with the unmarked Roberto Firmino watching on.
It is now one goal in seven games for Salah. Klopp won't be panicking just yet, but he will certainly be eager for him to rediscover his scoring touch against Manchester City back at Anfield.
Liverpool's improved defence has been a key factor in their strong start to the season, with just three goals conceded in their first seven Premier League games, but while they almost held on for a goalless draw at the Stadio San Paolo, their backline looked far from secure.
Even the normally unflappable Virgil van Dijk looked jittery in the first half, needlessly slicing a clearance out for a corner on one occasion and allowing Milik to fire a dangerous shot at Alisson on another, but it was in the second half that Liverpool's problems really began.
Napoli cut them open time and again, with substitute Dries Mertens striking the crossbar before they eventually got their winner. By the end of the game, they had amassed 14 shots on goal in total. It was the most Liverpool have faced in any game all season. Can they tighten themselves up again in time for Sunday?