Atletico Madrid's 3-2 victory over Liverpool has caused plenty of debate.
Diego Simeone's men weathered the storm throughout the first 90 minutes at Anfield, resisting wave after wave of attacks, before pouncing on a dreadful mistake by Adrian in extra time.
It was a rough and tumble approach to the game that left Jurgen Klopp spitting feathers in his post-match press conference, bemoaning Atletico's brand of football.
"I am completely happy with the performance. It's so difficult to play a side like this," Klopp informed BT Sport. "I don't understand with the quality they have the football they play.
"They could play proper football but they stand deep and have counter-attacks. I realise I am a really bad loser, especially when the boys put such an effort in against world-class players on the other side who defend with two rows of four."
Liverpool 2-3 Atletico Madrid
However, on the other hand, some fans viewed Atletico's performance as a defensive masterclass in a similar vein to many of Jose Mourinho's 'park the bus' displays over the years.
It's ultimately a subjective matter, but there's no debating that Atletico's tactics were both unappealing and completely apt for their opposition.
So, bearing that in mind, we wanted to delve deeper into how Simeone set up his team for the trip to Anfield and YouTuber 'Nouman' is one of the best in business when it comes to tactics.
Tactical analysis video
The online creator, who is approaching 250,000 subscribers, published a tactical breakdown of the game which highlights Simeone's 'defensive masterclass'.
If that phrase makes your skin crawl in relation to the game at Anfield, then hold your horses for a second and check out the video below. Then, keep scrolling for our full breakdown of the points.
What Liverpool did well
Atletico sat back and barely pressed, making it easy for Liverpool to move the ball from defence to midfield and Roberto Firmino dropped deep to create a 3 vs 2 overload in the centre of midfield.
This largely created space for Alex Oxlade-Chamberlain in the half-space on the right flank, while Koke and Thomas Partey were occupied marking Firmino and Georginio Wijnaldum.
That very tactic to dislodge Atletico's 4-4-2 formation resulted in a brilliant early chance for Oxlade-Chamberlain, which Jan Oblak saved, and his cross for Wijnaldum's opening goal.
How Atletico responded
In response to this, Atletico shifted across the pitch depending on where Liverpool had possession with their wide men - Saul Niguez and Angel Correa - focusing on central midfield as opposed to their opposing full-back.
This meant that Atletico marked every member of the Liverpool midfield, meaning the only player free was the full-back opposite to where possession was being held.
As a result, Liverpool were forced to play long diagonal balls - Jordan Henderson and Virgil van Dijk contributed 13 alone - and Atletico would shift their markers accordingly whenever this happened.
This forced Liverpool to carry out this move rapidly, but any transitions out wide were less dangerous to Atletico than through the centre given Stefan Savic and Felipe's prowess in the air.
How Atletico caught out Liverpool
That's all well and good, but Liverpool's two goals meant that Atletico had to attack themselves and they played a patient game of waiting to play long balls that would isolate Van Dijk and Joe Gomez.
If this was well-timed, Joao Felix and Diego Costa, unburdened by pressing responsibilities, would have equal numbers on the Reds' backline and were able to forced individual errors as a result.
They admittedly need some luck still, Henderson and Van Dijk could have done better for the second goal, but the lack of organisation was forced by Atletico's focus on quick transitions.
It all comes down to the fact that Atletico were more clinical with their chances.
Considering how many opportunities Liverpool had to score, it seems a little ham-fisted to suggest that Simeone executed a 'masterclass', even though he adapted intelligently during the game.
Rather, he knew it was best to sit tight and suffocate Liverpool in order to rob them of their quick transitions, frustrating them until they carved an opening to pounce on the counterattack.
It was football's answer to guerilla warfare and that's often the only way to topple major powers.
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