Liverpool are stepping into the unknown.
For 80 minutes at Goodison Park on Saturday, there was a rare sight: Liverpool playing a Premier League match without Virgil van Dijk at the heart of their defence.
Jordan Pickford's brutal - but unpunished - challenge, which has left Van Dijk needing surgery on his knee, means it is something Liverpool will now have to get used to.
But how will they cope without their star centre-back?
The brilliant Dutchman has played in 95 of the 96 Premier League games Liverpool have had since he made his debut in January 2018. He played every minute in the league last season, as they claimed the title for the first time in 30 years.
So how do they try to cover the absence of a player who has been central to their triumphs domestically and in Europe over the past three years?
It is a huge task and, with Premier League and Champions League games coming thick and fast, it is a task Jurgen Klopp must get right if Liverpool are to continue to be successful. That is how pivotal Van Dijk has been.
The difference Van Dijk has made
Critics who suggested the £75m fee Liverpool paid Southampton for Van Dijk was extortionate have long since conceded their case in that argument. Van Dijk has, if anything, been a bargain for Liverpool, transforming their defence and providing the platform for the Reds to become arguably the best side in Europe.
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Liverpool had let in 120 goals in their 96 Premier League fixtures before he arrived. They have conceded just 78 in the 96 since.
He has helped Liverpool keep 43 Premier League clean sheets in that time, the most of any player in that period.
Handily, he has also scored six headed Premier League goals since the start of last season. Only Dominic Calvert-Lewin has scored more.
But beyond the numbers, it is the reputation Van Dijk has honed, the respect his towering 6ft 4in frame commands, and the authority he brings to - and inspires in - Liverpool's backline which has been the real factor in transforming Liverpool.
From March 2018, Van Dijk went 50 games without being dribbled past. It was an outrageous stat - but how much did that play on the mind of opponents; how much do opposition sides adapt their usual attacking patterns because they are intimidated by the 29-year-old?
In Pictures: How Van Dijk's injury happened
Interestingly, there have been some unusual slip-ups from Van Dijk this season. Against Leeds, his over-confident clearance allowed Patrick Bamford to score. He only made one error leading to a goal in all of last season. Then there was the 7-2 drubbing by Aston Villa, where questions were raised about Liverpool's high line.
They have let in 13 goals in five games this season. It took them 15 matches to concede that many in 2019/20.
But despite those errors and frailties, stepping in for Van Dijk is going to be no easy task. And Klopp is short on options.
Joe Gomez came off the bench on Saturday, playing alongside Joel Matip who had started ahead of him. Afterwards, Klopp described his performance up against the in-form Calvert-Lewin as "sensational".
But Calvert-Lewin had risen above Gomez and Andy Robertson to head in Everton's equaliser. Earlier, with Van Dijk out of the game, Michael Keane had outjumped Liverpool's players at a corner to head in Everton's first.
That, though, will be Klopp's strongest pairing while Van Dijk is out.
There are less straightforward alternatives: Fabinho could drop in from midfield to defence, while skipper Jordan Henderson has also played in the backline in the Club World Cup and at Wolves in the FA Cup, and Gini Wijnaldum played in a three-man defence against Brighton in January 2019.
|Weds October 21||Ajax (away)||Champions League|
|Sat October 24||Sheff United (home)||Premier League|
|Tues October 27||Midtjylland (home)||Champions League|
|Sat October 31||West Ham (home)||Premier League|
|Tues November 3||Atalanta (away)||Champions League|
|Sat November 7||Man City (away)||Premier League|
Beyond the first-team regulars, following Dejan Lovren's departure in the summer, Klopp would have to draw from Liverpool's academy sides.
Billy Koumetio is highly rated and would have made his debut in cup competitions by now if not for badly-timed injuries but there would be huge pressure on the 17-year-old to step in. Rhys Williams, 19, has featured in the Carabao Cup, Sepp van den Berg, 18, is also well thought of. Then there is 23-year-old Nathaniel Phillips, who looked like he was heading to the Championship on loan last week.
It's a concern, given Matip - who has played just 165 minutes of Premier League football in 2020 - missed substantial game time last season and only returned on Saturday from a muscle problem which had kept him out since the opening weekend win against Leeds, while Gomez has had injury issues in the past too.
It is significant Van Dijk's injury came the day after the domestic transfer window closed. It is a long two-and-a-half months until the January window allows Liverpool to bring in reinforcements.
How Liverpool will cope during that period - and beyond until the end of the season - is impossible to predict.
They have been shorn of their defensive leader, the Premier League's best defender, and they are short on back-up.
Now we will see how well they can adapt. Now, we will also likely see just how important Van Dijk has been.
Sky Sports' Jamie Carragher:
"The big question you're looking at now is, can Liverpool win the league without Van Dijk there? I think it blows the title race wide open, I really do.
"I still felt at the start of this season Liverpool were the team to beat. I think with Van Dijk being out for what looks like the whole season now, I think it's going to be all on for Liverpool.
"I think Liverpool certainly have to go into the market in January, and not just because of Van Dijk's injury, but Liverpool were weak in that area anyway. They lost (Dejan) Lovren before the start of the season now the other players in those positions are very injury prone."
Pitch to Post podcast: Has Van Dijk injury derailed season?
Was Saturday the day Liverpool's title hopes took the cruellest of turns?
Jasper Taylor is joined by Gerard Brand, Ben Ransom and Keith Downie to dissect the weekend's action in the Premier League, leading of course with Van Dijk's ACL injury and what that might mean for the champions.
Why did Liverpool not buy a centre back last summer?
Analysis by Sky Sports' Richard Morgan:
People maybe waking up this morning asking why, in light of Virgil van Dijk's potentially season-ending knee injury, Liverpool did not sign a central defender in the summer transfer window.
The Premier League champions sold experienced Croatia centre-back Dejan Lovren to Zenit St Petersburg in July, leaving them with just three recognised central defenders, one of who - Joel Matip - has had a questionable injury record during his time at the club.
However, while sporting director Michael Edwards did reportedly assess a number of possible targets, including Napoli's Kalidou Koulibaly, Brighton's Ben White and Sevilla's Diego Carlos, in the end the club decided against entering the market for a number of reasons.
Firstly, neither of the trio would come cheap, with Manchester City turning their attentions to Ruben Dias after reportedly being told Koulibaly would cost them £70m, while the highly-rated White signed a new four-year deal at the Amex in September.
With Liverpool already in possession of the meanest defence in the Premier League from the previous two seasons, it was thought unnecessary during the Covid-19 pandemic to spend those sums on a player who may not actually improve the back line.
Meanwhile, questions about Liverpool being short on numbers at the heart of their back four, with Lovren having not been replaced, were then answered by Fabinho again seamlessly deputising for the injured Joe Gomez and Matip in producing a man-of-the-match display in the side's 2-0 win at Chelsea in the second league game of the campaign.
So in effect, Jurgen Klopp had four centre backs at his disposal going into the season and given Van Dijk had only missed one top-flight match since moving to Anfield in January 2018, the thinking understandably was the club did not need to strengthen that area of the team.
However, that decision may now come back to haunt them…