Good luck Erik ten Hag.

When Manchester United announce – as expected – the Ajax boss as their next permanent manager, social media will be flooded with suggestions of what he needs to do or fix to get the club challenging for titles again, and it's going to be a long list.

On the evidence of United's performances against Liverpool – who will surely be one of the two teams to beat again in 2022-23 – this term, the chasm between the Old Trafford club and the best is at its widest in a generation.

Liverpool crushed them 5-0 at Old Trafford in November, though Tuesday's 4-0 loss at Anfield was arguably worse and probably even had interim manager Ralf Rangnick considering his own future.

The most ardent of Man Utd fans would've been feeling glum pre-match about their chances here, though there would always be a hint of 'what if'.

It's football. There could always be a freak goal, a comical own goal, one moment of individual brilliance. Throughout the history of the sport there have been countless examples of teams absorbing pressure for 90 minutes and stealing a winner.

As bad as United have been at times this season, and as good as Liverpool are in general, fixtures like this bring a sense of unpredictability – or at least they're supposed to.

As arguably the most recognised and historic rivalry in English football, the minimum one would've expected from United was a bit of desire to get one over the Reds, maybe dent their quadruple hopes. But there was no sign of such spirit until it was already too late.

Frankly, United's first-half performance was a joke. Sky Sports pundit Gary Neville, a former Red Devils captain, said before the game that this was their worst team in "30-40 years", and it was difficult to disagree with him come half-time.

Of course, it should be said that this wasn't just about United being poor: Liverpool were excellent for much of the game. Thiago Alcantara was a joy to watch in midfield as he almost single-handedly pulled Rangnick's defence and midfield this way and that. Even the Spain international's inaccurate passes were satisfying to see because you saw the invention and vision behind them.

But it was the speed, directness and ruthlessness that typifies this Liverpool team that brought the fifth-minute opener, as they cleverly worked space on the right in their own half before Sadio Mane released Trent Alexander-Arnold, who subsequently picked out Luis Diaz for a tap-in.

Their second goal was even better as they retained possession and sliced through United with a one-touch passing move that culminated in an outrageous Mane reverse pass over the defence for Mohamed Salah to collect before slotting home.

But the lack of character their visitors showed was astonishing. Liverpool seemed to have the freedom of the pitch, they passed through midfield as if Nemanja Matic, Jesse Lingard and Bruno Fernandes weren't there. Players were walking.

United reached half-time without a single shot, a first in the league since April 2018. Granted, they went on to beat Manchester City 3-2 on that occasion... But even the suggestion that something similar might've been on the cards here would've drawn laughter.

Similarly galling was the fact United only committed two fouls in the first 45. Without wanting to sound like Roy Keane ("you know what I might do, I might smash into somebody, just to make me feel better!"), when being played off the park a degree of petulance is almost to be expected, but they couldn't even muster that level of frustration.

Things did change briefly after the interval. Rangnick ditched his back three and introduced Jadon Sancho, and suddenly United looked... functional. Players were running, they were hounding their counterparts. They had a shot, then a second. A whole two shots!

Jurgen Klopp stood aghast on the touchline in the 65th minute, his mouth gaping for a full 10 seconds after Alisson had to make two saves in quick succession – they didn't count technically in the stats because an offside was erroneously given, but the Brazilian undoubtedly denied a goal that would have been given by VAR had they scored.

But United's brief improvement said more about Liverpool's post-break drop-off, and they soon snapped out of it – three minutes later it was game over, if it wasn't already. Andrew Robertson made an interception ahead of Anthony Elanga, then Diaz's pinpoint cross was expertly turned in by Mane.

Salah completed the scoring late on with a deft finish that was helped by a slight deflection. While there was a hint of fortune, it ensured the scoreline greater reflected the Reds' dominance.

The nine goals United have conceded to Liverpool this season is the most they've ever shipped against one team in a single campaign. Their 9-0 aggregate loss to the Reds over 2021-22 is their worst to one opponent in the league since 1892-93. Yes, that's 1892, not a typo of 1992.

Much of the build-up to this was dominated by talk of club structures, recruitment and 'synergy', but honestly, fans will just hope Ten Hag can instil a bit of fight, assuming he's not run for the hills already.