Pep Guardiola arrived at Anfield in a charcoal flat cap and would have departed his Main Stand seat with a catalogue of mental notes on Liverpool’s authoritative front foot play.
If the Manchester City manager wasn’t already fully clued up on the attacking juggernaut his men will face at this ground on New Year’s Eve, the Reds’ 4-1 victory over Stoke City provided a three-dimensional picture.
This was not Jurgen Klopp’s side at their blinding best, nor even close to their commanding apex, but they were still formidable against a team drafted to make them rough it out.
Mark Hughes’ decision to start with Xherdan Shaquiri and Bojan on the bench ensured there was no ambiguity over his intention to inflict an aerial onslaught on Tuesday night.
The 53-year-old’s selection was heavily criticised pre-match, but his thinking was applauded on 12 minutes. Liverpool allowed Erik Pieters to cross with little pressure from the left, with Dejan Lovren losing Jonathan Walters, who headed in past Simon Mignolet from an acute angle at his near post.
It was passive all round from the hosts, and Stoke duly punished them. The Potters could’ve increased their advance shortly afterwards, with the ball breaking to Joe Allen following a scramble in the area, but Mignolet did well to thwart his former team-mate.
"It became a wild game and when they had the ball it was immediately in the air and Crouch was outstanding," explained Klopp.
"Obviously Mark Hughes likes to bring Crouch against Liverpool; I don’t know exactly how often we have played them now, but Crouch was always involved I think."
The Anfield outfit had not conceded first on their own turf in the league since May, but any fears that they would capitulate after the early setback were quickly quashed. To 'strike back' - one of Klopp's fundamental tenets - is now seemingly tattooed to their psyche.
The Merseysiders revved up and rolled out attacks en masse as they tried to regain authority in the encounter. Peter Crouch cleared a Roberto Firmino effort off the line, but the resistance would not last.
Stoke, like several others before them this season, learnt that a template to disrupt Liverpool is good in theory, but gruelling to put into practice.
And despite having early warnings prior to taking the lead of how the Reds could thread through and tear them apart, they were punched square on in a 10-minute spell that ensured it was game, set, flock forward for Liverpool.
Divock Origi fed Sadio Mane on the right with a wonderful pass and the Senegal international in turn supplied Adam Lallana. The 28-year-old met the ball, which cannoned off Glen Johnson and landed back at his feet.
He planted a tidy finish past Lee Grant from a tight angle to record his seventh goal of the season - equalling his total for the entirety of 2015-16. With half-a-dozen assists in the league as well, no midfielder has contributed more successfully in the final third than Lallana.
Stoke were again surgically dismantled before they could recover any sort of organisation. Lallana took possession on the left, displaying fine footwork before linking up well with James Milner.
The full-back set up Firmino and made a run to receive a one-two that drew in defenders, allowing the Brazilian space to send a left-footed drive across goal.
The effort went in off both posts and Liverpool went into the interval as the dominant force.
After the break, there was a bombardment - but not the aerial one Hughes had envisaged his side inflicting. They were at the mercy of the Reds’ flowing football; their movement crisper and telepathy cranked up.
Stoke were helpless and hapless as Liverpool swarmed. Giannelli Imbula covered Origi’s cross into his own net under pressure from Mane, who was primed to tap in.
And if it wasn’t bad enough for the visitors, Klopp had the luxury of introducing Daniel Sturridge and Emre Can on 70 minutes.
The striker scored his first Premier League goal of the season, and fifth in all competitions, as he pounced on a poor backpass from Ryan Shawcross.
Sturridge rounded Grant to secure Liverpool’s fourth before wriggling his arms as Anfield bounced just 56 seconds after he entered the pitch.
"I heard Pep Guardiola was in the stadium tonight; I am not sure he watched a lot of games in the last few weeks from the stadiums of the opponents, so that’s a first sign it’s a special game and we are already looking forward to it," Klopp said afterwards of the meeting on December 31.
"It’s a difficult game for both teams, but exciting and the best thing is it’s at Anfield. I am really looking forward to it. They are an outstandingly good side and we are not too bad, so it will be a nice game."
Second in the standings, the highest scorers in the division, and constantly showing the appetite to scale new obstacles, the Reds are in no mood to surrender.
Guardiola most certainly noted that.