For a brief and fleeting period at the beginning of their game against Milan on Wednesday night, the Liverpool of 2017-2020 were back - and they were back with a bang.
They have offered glimpses of returning to their former glory already this season, but nothing has been quite as exquisite as this.
During the first 15 minutes of their eventual 3-2 victory, Jurgen Klopp's charges hunted like rabid dogs, barely allowing the Rossoneri out of their own half. For the first time in a long time in Europe, Klopp's previously well-oiled machine was firing on all cylinders.
The obscene counter-pressing, the quick exchanges, the intoxicating Anfield crowd firing the players up like a shot of amphetamine - it was all here in abundance.
The stats from that scintillating quarter of an hour are quite something. Liverpool registered 11 shots to their opponents' one, and they also forced Milan into seven clearances. The Reds' scored during this period too.
It came from a source that has proved so fruitful in the past with Mohamed Salah slipping the overlapping Trent Alexander-Arnold through, who fired a cross into the unfortunate Fikayo Tomori, with the ball ending up nestling in the back of the net.
They should have been two up soon after as well. Milan were penalised for a handball in the box following excellent work by the terrific Andrew Robertson, only for Salah to do something that he never normally does - miss a penalty kick.
At the time, this felt inconsequential. Milan had barely had a kick, let alone threatened Alisson's goal. Surely it was only a matter of time until the Reds managed to pry the floodgates open and give the Rossoneri a humbling welcome back to European football's top table.
Incredibly though, half an hour later, the half-time whistle was blown and Liverpool were trudging down the tunnel on the wrong end of a 2-1 scoreline.
The goals were scored within less than two minutes of each other. For the first, Joel Matip was caught ball-watching while Liverpool's midfield were guilty of some slack marking. For the second, Matip was unlucky, but Milan's ability to slice through the Reds in transition was alarming.
The turnaround was essential viewing for the neutral but Klopp would have watched on in dismay. This sort of thing could have been expected last season - when the Reds had a lovable but shabby centre-back pairing for most of the group stages - but now they are back to full strength, it drew uncomfortable parallels with the Liverpool of Klopp's early years at the club.
Devastating in patches, yet seemingly unable to control games when it mattered.
In the end, they got the job done, partly thanks to a piece of magic from Champions League rent-a-moment man Divock Origi, and partly thanks to Jordan Henderson channeling the ghost of Steven Gerrard in the 2006 FA Cup final.
Being able to secure the three points deserves credit, but Klopp will be concerned about his side's lack of ability to get the game won much earlier. Liverpool must rediscover their ability to control things if they are to make a serious claim for the Champions League this season.