When Liverpool came into the dressing room at half-time, shell-shocked and 2-0 down to a Villarreal side they had dominated only a week ago, Jurgen Klopp asked his coach Peter Krawietz to assess their tactical performance in the first half.
The loyal assistant was asked by Klopp to find any instances of where they were successfully carrying out their tactical plan so he could show his players what they needed to do. Krawietz "couldn't find any", according to Klopp, such was the catastrophic nature of their first-half display. In an attacking sense, that evaluation of their tactical misgivings may be true. But defensively, it was a case of Villarreal coach Unai Emery preparing extensively to find their weaknesses.
It would not classify as new information to suggest the Reds are more vulnerable down the right flank, with Mohamed Salah taking up an advanced position up front and Trent Alexander-Arnold's tendency to get forward. But it was the manner in which Villarreal took advantage of that glaring void down the right that showed Klopp where his side can be hurt, and Pep Guardiola must have been watching with a keen eye and jotting down some notes too.
Emery spots weakness
Setting up in a narrow 4-4-2, Emery focused all of his efforts on punishing Liverpool's laissez-faire attitude towards defending on that side. It took all of three minutes for Villarreal to put that plan into action. From Liverpool 's perspective, it was an entirely avoidable goal to concede. Much could be said about the deafening atmosphere in the intimate Estadio de las Ceramicas and how Liverpool felt intimidated from the start. However, it was a goal that was crafted from a cunning move and nothing more.
Villarreal gambled by overloading the left side, with full-back Pervis Estupinan providing the width in the channel. The Ecuadorian's whipped cross found Etienne Capoue at the far post and the Frenchman's pass found the onrushing Boulaye Dia to strike home. Capoue knew that he had a chance of finding a yellow shirt at the back post because along with Dia, Gerard Moreno, Francis Coquelin, Giovani Lo Celso were waiting to pounce on the squared ball. As a contrast, Liverpool only had Ibrahima Konate and Virgil van Dijk positioned to deal with the danger in the middle.
Villarreal committed men forward, but it was interesting that Emery's men were all positioned on Alexander-Arnold's side of the box. The right-back was left in an area of space where he couldn't close down the cross - that job was left to Naby Keita only for the Guinean to fail to stop the delivery - and could only watch on as Dia met the inviting cutback to slot home.
Trent struggles with overload
That would prove to be the theme of the half for the hosts. Estupinan, again not tracked by Salah, had the freedom to surge forward at will and cause Alexander-Arnold a defensive dilemma, not knowing whether to go with the midfield runners or stay in his position. Even with help from Keita, it was an area that would be exploited several times throughout the half, including when Lo Celso was brought down by Alisson Becker in the penalty area, only for referee Danny Makkelie to wave play on.
The second goal made a more glaring representation of Alexander-Arnold's struggles to cope with the left-side overload. Once again, it was Capoue who had strode upfield and muscled his way past Andy Robertson to find space for a cross. This time he hung it up towards the back post without even looking up, knowing that yellow shirts would be queueing to head home.
Having scored the first goal, Dia made a brilliant unselfish decoy run that essentially made the second. Whether it was planned or purely instinctive, the striker darted into a central area and forced Konate to go with him. In doing so, it left the space wide open at the back post for Coquelin to plan his trajectory, and the former Arsenal man had a jumping start on the static Alexander-Arnold to expertly guide his header into the top corner. If it hadn't been him, Estupinan was waiting to slot home instead.
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Klopp finds the fix
It was only at the interval when Liverpool were able to fix the problem. Alexander-Arnold came out in a more advanced position to push back Estupinan and eliminate the threat of the overload. Keita was also present in the half spaces, giving the Reds more fluidity and angles to play through the lines and find their devastating front three, as Klopp referenced in his post-match interview: "All of a sudden when we broke the lines, when we found Naby and Trent in the half-spaces, and when the front three were more flexible, not fixed in position, all of a sudden we were in the game, scored goals, and made it happen." he said to BT Sport.
Of course, the injection of pace from Luis Diaz proved crucial in giving Klopp an outlet on the left that he didn't have with Sadio Mane or Diogo Jota in the first half. And the Colombian was simply sensational in the second half, as reflected by his part in the second goal and when he scored the third to complete a brilliant 3-2 comeback.
But while Klopp will be happy with the response and character shown by his side, the issue of what to do with Alexander-Arnold will have to be ironed out before their Champions League and FA Cup finals. In games where the finest margins or smallest errors can prove to be a turning point, the Merseyside outfit cannot afford to have such an obvious ailment. If Emery can find their weakness, one can only imagine how Guardiola or Thomas Tuchel will seek to punish them for it.
