Dejan Lovren's nightmare day came against Tottenham at Wembley in October. Having been culpable for two goals, the centre-back was substituted after just 31 minutes after a calamitous performance in what would ultimately be a 4-1 defeat for Liverpool.
In Sunday's reverse fixture at Anfield, the 28-year-old lasted the entire game, which ended in a 2-2 draw. What has changed in four months? Very little; the Croatian international is still prone to making catastrophic mistakes.
Lovren's sliced clearance with three minutes left led to a Spurs penalty, but, luckily for the defender, Harry Kane missed the spot kick. While it is unusual for the Spurs striker to make such an error when under intense pressure, the Liverpool man too often blunders when the stakes are highest.
Jamie Carragher, who knows what it is like to anchor the Anfield defence, encapsulated not just Lovren's performance at home to Spurs but, perhaps, his Anfield career: "It sums Dejan Lovren up as a footballer. He had a great game but lets himself down with a stupid mistake."
It is possible to have sympathy. Since his arrival from Southampton four years ago, Lovren has been surrounded by players who do not inspire confidence, and he also felt he never received the protection from midfield that he had been given at St Mary's.
Under Brendan Rodgers initially and then Jurgen Klopp, Lovren operated in a back four that sometimes looked thrown together without any plan or purpose. Both managers seem to regard defence as an afterthought. Moreover, what Liverpool needed was a leader, but Lovren does not have the personality to take that role.
He has been subjected to an unacceptable level of abuse on social media, and after the Tottenham debacle in October, went public about receiving death threats over the internet.
It is legitimate, however, to ask whether Lovren should play regularly for a team chasing a top-four spot in the Premier League and competing in the last 16 of the Champions League. And for that, Klopp must take his share of blame.
The manager has been at Anfield for nearly two and a half years, which is ample time to revamp the squad he inherited. The Klopp effect is obvious in the attacking department -- Liverpool's approach going forward is thrilling -- but defensively they have not improved at all.
Goalkeepers Loris Karius and Simon Mignolet give their defenders little sense of security, although Karius showed signs of improvement against Tottenham. He was criticised for the punch that led to Victor Wanyama's equalising strike, but the goal summed up Liverpool's wider defensive travails.
When Christian Eriksen shaped to cross from the left, Virgil van Dijk and Joel Matip found themselves in no-man's land. Neither picked up a man nor moved to cover the near post. As such, Karius was forced to take up a stance closer to the post than he would have liked.
If the defenders had taken correct positions, their goalkeeper would have been nearer the middle of goal and able to catch the ball easily. Lovren, meanwhile, let Kane get goalside and was ball-watching as the Spurs striker peeled off toward the back post. It left Karius with little option but to punch the cross, but even then, Liverpool had opportunities to clear.
Emre Can was tracking back and should have been able to help the clearance upfield, but the midfielder reacted too late. Alex Oxlade-Chamberlain was slow to close down Wanyama, who smashed home from 30 yards. It was another goal where responsibility could be shared around the Liverpool defence and midfield.
With 31, Klopp's side have conceded more goals than the other teams in the top four, which compares badly to Manchester City (19), Manchester United (18) and Chelsea (23). They have scored 59 goals at the other end and Mohamed Salah is having a standout season, but the effect of his 21 league goals is being undermined by Liverpool's inability to stop opponents.
Sunday was a microcosm of this: Twice the Egyptian forward gave his team the lead, twice Spurs got back into the game as a result of defensive inadequacy. Lovren's error for the first penalty made it a hat trick of gaffes; Klopp's team were lucky to escape with the draw.
Van Dijk's £75 million fee suggested that he would be an instant cure for systemic issues, but it will take more than one player to solve the problems. He has the physique and leadership qualities to thrive and dominate in the back line, but he cannot afford to be caught in the chaos.
Lovren keeps making the same mistakes and not even Klopp's famed inspirational management techniques have changed that. If there is no significant improvement before the end of the season then both club and players need to move on.
But the evidence of four years is that he is a lost cause. Lovren has had enough chances, and until Klopp finds a way to tighten up in defence, Liverpool will continue to lurch from effervescent to embarrassing.