Liverpool are in need of a reaction.
They may well be doubting themselves after Aston Villa, wondering if everything that made them champions of England for the first time in 30 years has been found out.
A 7-2 defeat will do that to you.
Liverpool will bounce back, they're too good not to. But their next task is about as tough as it gets.
Everton are leading the Premier League and, buoyed by Carlo Ancelotti and some excellent summer signings, head into the derby in confident mood.
But Jurgen Klopp will have a thing or two up his sleeve for the meeting with the neighbours.
And that could involve going back to the future in order to settle his problems.
The German used a 4-2-3-1 formation in order to get the best out of Mohamed Salah and include new signings in Liverpool's starting line-up in late 2018.
It was a change that helped Liverpool spark into life during the Autumn, as the Reds built up a head of steam and staged a Premier League challenge.
The switch simultaneously allowed them to stay solid at the back while unlocking more potential from their attack.
Xherdan Shaqiri, who had impressed in cameos beforehand, came into the team on the right of a three positioned behind Salah in attack. Liverpool swatted aside Cardiff City and both men scored.
The Reds would win nine of their next 10 games, including big victories over Arsenal, Newcastle and Manchester United.
It's a change that could work for Liverpool again now, starting in the Merseyside derby.
Thiago Alcantara enjoyed an impressive Liverpool debut from the bench against Chelsea, but the ruthless nature of a derby, it'd be wise to provide the Spaniard with a helping hand in midfield.
He could slot into a two alongside captain Jordan Henderson, whose energy and leadership would allow Thiago to put Liverpool's attackers into some dangerous positions.
That would mean, for the time being, that Fabinho drops back into defence alongside Virgil van Dijk, taking Joe Gomez out of the firing line for the time being, but the Brazilian could also be utilised in midfield depending upon the opposition.
Klopp would then have much greater freedom in attack.
Salah, who has been in brilliant form since the Premier League campaign began, would be free to operate in an even more advanced position.
The Egyptian is at the peak of his powers and enjoyed Liverpool's switch in 2018, scoring nine goals in the 10 games Liverpool went unbeaten.
Behind him, Sadio Mane would be slightly further back, allowing him to stay as involved in the game as he is now, while also putting Roberto Firmino in the midst of the action in an attacking midfield role.
Firmino has struggled this season but easing the pressure on him by allowing him a break from leading the line could be just the tonic to getting him back to his best form.
Liverpool then have an extra option on the right, with a number of candidates jostling for the position.
Diogo Jota has impressed in his short time at Liverpool so far, while Curtis Jones has emerged as somebody who is pushing for more first team minutes.
Meanwhile, Takumi Minamino has finally found his feet at Anfield and Shaqiri, who scored six goals from the same position in 2018, is hoping to reignite his Liverpool career.
Klopp also has the option of going more conservative, with Gini Wijnaldum or Naby Keita capable of playing in the role.
What's clear is that Liverpool now have an embarrassment of riches in midfield and attack - it's just about getting the best out of all of them.
A switch to 4-2-3-1 worked two seasons ago before Klopp moved back to 4-3-3 for a breathless run in that saw Liverpool pipped to the title by Manchester City.
There was no need for such a tactical move last term, with the Reds dominant throughout a glorious campaign.
But Klopp will know he can rely on an old friend to surprise Everton - and give Liverpool's season the early jolt it needs.
What formation do you think Jurgen Klopp should play against Everton? Let us know in the comments below.
