One day, a long, long time from now, it would be interesting to sit down with Ole Gunnar Solskjaer, in the unlikely event he could stomach reliving this humiliation, to ask him what plan - if any - he had in mind coming into this to try to muzzle Roberto Firmino.
Because, amid the fixation on and fear induced by man of the moment Mohamed Salah, Manchester United forgot all about the cat burglar Liverpool have in their midst.
Firmino’s work was done long before he exited the stage 14 minutes from time and slipped into a warm embrace with Jurgen Klopp - the manager all United fans secretly wish they called their own - as the Liverpool supporters momentarily halted their brutal taunting of Solskjaer to stand to acclaim their imperious No 9.
It was only marginally more fitting than Klopp’s eulogy to Firmino after the game. “Mo obviously gets a lot of attention and rightly so but Bobby Firmino, for people with football knowledge...I’m pretty sure when he finishes playing people will write books about how he interpreted the false nine position,” the Liverpool manager said with the deepest admiration.
“I won’t say he invented it but the way he plays it looks like it at times. He played outstandingly well.”
Players this clever are hard enough to shackle with a game plan. Take them on without one and you are simply asking for punishment and what was as deeply troubling was Solskjaer’s lack of response when it was clear to everyone inside Old Trafford that Firmino had United exactly where he wanted them.
Operating almost as an advanced midfielder at the tip of a diamond, Firmino revelled in that half space just behind or in between Fred and Scott McTominay and ahead of Harry Maguire and Victor Lindelof, who seemed in a perpetual state of confusion about what to do with the elusive Brazilian. Part centre-forward, part false nine, part playmaker and, on this day, a ghost as far as United were concerned.
Maguire should never have been drawn out to Firmino for Liverpool’s first goal inside five minutes but this is what he does - he creates uncertainty, drag players out of position, he teases and torments.
United were already like dominoes falling before Diogo Jota prodded the ball through to Firmino in the inside left channel just over the halfway line but his positioning was immaculate and set the tone for what was to follow.
Behind him he had McTominay scrambling to come back, ahead of him he sucked Maguire out and from there slipped a perfect pass into Salah who, with the help of Luke Shaw playing too deep, played in Naby Keita to score. It was like Firmino was playing chess all day with United and constantly had their players in check.
It was not just Firmino’s quality on the ball, though. His efforts out of possession are fundamental to Klopp’s press and that work-rate shamed United’s own forwards, whose half-hearted approach to closing down space was one of a litany of fault lines on a truly wretched day for the club.
When Salah scored his third and Liverpool’s fifth shortly after the restart, it stemmed from Firmino rushing back and hounding Paul Pogba off the ball before Jordan Henderson released Liverpool’s top scorer with a stunning pass. “What he did defensively was absolutely insane,” Klopp said.
Liverpool were everything United were not: organised, bright, sharp, incisive, committed, hungry, technically accomplished and with complete clarity about their roles and their manager’s intentions. In Salah, they also have an executioner and Firmino, most obviously, revels in the attention the Egyptian attracts given how much space it frees up for him to exploit.
Firmino was not the orchestrator of Liverpool’s third goal but it did provide a neat snapshot of the panic Salah invites. You could have thrown a blanket over United’s back four, McTominay and Mason Greenwood as they were all drawn, like a magnet, to Salah.
It left the right side totally free for Keita to speed into and cross for Salah, whose reaction to his shot being blocked by Maguire was half a second quicker than anyone in a red shirt.
After a trying last season, Liverpool are back with a bang and, with Manchester City and Chelsea also flying, the Premier League could be shaping up for a genuine three-horse title race.