A year ago, Manchester United were outclassed, and their manager Ole Gunnar Solskjaer appeared completely out of his depth after an Anfield masterclass by the Champions-elect.
Here in the same venue, the visiting side not only displayed their progression under a manager who has clearly evolved along with his team, but also exposed the gaping black hole that threatens to suck the life out of Liverpool ’s title defence.
It was a game where Jurgen Klopp’s side were required to stand up and show their true quality, after a miserable run since the middle of November which has seen them take 14 points from their last 28.
Yet at the end, they will feel slightly relieved to have escaped with a point in a top of the table contest where Manchester United perhaps showed a little too much respect for their rivals…and not enough ruthless intent to pursue the own now very real title ambitions.
Solskjaer’s team came with an understandable game-plan of swamping defence to blunt the attacking threat of Salah and Mane, and perhaps nick a goal on the break.
But as the cagey contest progressed it became increasingly obvious they possessed a very real height advantage against a team who were again forced to employ two midfielders as stand in centre halves.
United could, and should, have thrown the ball into the box more, especially at set pieces.
There are no rules to say you have to play pretty football in a title race, and here the blunt, brutal approach would surely have been effective.
But they will still be happy with a point, which showed, after they weathered a difficult first half hour as Liverpool created a few chances, they are now very much in the hunt for the Premier League crown, with a second half that deserved more.
In fact, it was only three fine saves from Alisson in the space of six second half minutes that denied them victory.
United may have cause to regret the failure to turn their second half advantage into three precious points, but still they have exposed Liverpool’s weakness.
And it could be a fatal one, in this season’s race.
They failed to score for a third successive game – the first time since 2005 since that has happened in the league – with Firmino and the unlikely source of Andy Robertson both spurning a couple of chances in the first half.
Yet it is so painfully easy to see where the real problem lies. Both Fabinho, who was excellent, and Jordan Henderson performed well enough in defence, but their presence in midfield was so badly missed.
As the game progressed and United’s confidence grew, you could see the uncertainty in the home side, as they looked more and more to that gaping hole at the back.
It is a black hole that sucks the confidence out of every part of the pitch. And it doesn’t feel an over-reaction to suggest that unless Liverpool’s hierarchy sort out the problem, they not only will they struggle to defend their crown, but they could even finish outside the top four, on this current run of form.
They perhaps have two weeks to find a centre half to save their title defence.
Only in the opening half hour did they look anything like the real Liverpool. Firmino had a glorious chance on 17 minutes when Mane’s good work saw the ball fall to him in the box.
Robertson too, blazed over when well positioned soon after and early on had a better chance than he realised.
The best moment of all for the home side, though, fell to Firmino on 34 minutes, when Salah’s run gave him a simple finish, but he mis-hit the shot which cleared off the lunge of the excellent Harry Maguire.
Maguire produced to more fine blocks in the second half, but really it was mostly United’s game by then, with Alisson saving brilliantly from Fernandes after Shaw’s fine cross, then denying Pogba from close range, and Rashford from a corner.
They were three big chances, but perhaps the biggest threat of all came from every set piece, especially after Edison Cavani came on.
Why United didn’t go route one more is a mystery, but you can be sure Burnley won’t make the same mistake when they come here on Thursday.