Comment: Klopp and Mourinho need more than huff and puff
Twenty minutes into Saturday night's game against Atletico Madrid, Barcelona were attacking down the left side when an attempted through ball was intercepted. The next Barcelona player to touch the ball was Marc-Andre ter Stegen, the goalkeeper, as he picked the ball out of his net.
What happened in the intervening 55 seconds should form a study on why nominally defensive teams should try to keep the ball and not simply whack it up the pitch and hope for a few breaks.
Antoine Griezmann was initially the point-player who switched it to left-back Filipe Luis. With nothing on, they went to the right wing; when that avenue closed, it was back to the centre and out to the left again. The process repeated itself with subtle movement and clever passes that were rarely at risk of interception and shifted the Barcelona defence until they found a point of weakness.
There were 19 passes in the move, of which, including the interception, four were played with one touch as players trusted their technique. Crucially, having spotted the weakness, two of those one-touch passes opened up the defence.
From the left Luis popped the ball to Yannick Carrasco; he spun and found Saul, who had seen that Ivan Rakitic had switched off for a split-second, and found space in behind the Barcelona midfielder.
From just outside the box, he drilled a right-footed shot to the bottom corner to put Atletico in front.
It's often unfair to compare different teams in different leagues, but for anybody who sat through Manchester United's nullification of Liverpool earlier in the afternoon, it was something of a tonic.
Overall, Atletico have inferior players to Barcelona, but they recognised their team could still cause problems - albeit with the risk that if they lost possession in key areas they would be susceptible to rapid counter-attacks from two of the best attackers in the world.
Barcelona, too, may have been wary of the threat posed by Griezmann, yet they trusted their quality and eventually found an equaliser. Both managers deserved to be happy with their evening's work because they gave their teams a chance to win and, having failed to do that, managed not to lose.
The difference at Anfield was the fear which gripped both sides.
Afterwards, Jurgen Klopp complained about United's tactics with a less than veiled dig at his rival, saying: "You could not do this at Liverpool. Obviously for Man United it is OK. It's quite difficult when a top-class team like Man United has that defensive approach."
Klopp's biggest problem, however, is that it's not just "top-class teams" who take the defensive approach and, until he finds a way around that, the cycle will continue.
At times Klopp's Liverpool resemble the wolf from the story of the Three Little Pigs.
They can blow the opposition's house to smithereens once it is made of straw or wood. Build it with bricks, however, and they huff and puff, with tactics that boil down to 'if Plan A doesn't work, keep trying Plan A'.
At least in the story there was no moaning that 'you could not do this as a wolf, obviously for a pig it is OK'.
Unlike in the past, Liverpool didn't try the wolf's approach of coming down the chimney and ending up with the scalding of a breakaway goal against them. Had they done so, Mourinho insists he would have boiled the pot of water in the fireplace.
"I was waiting for them to make an offensive change to try more but he never did it. He was afraid of our counter-attack," insisted Mourinho, who praised his teams "tactical discipline and organisation".
Mourinho is a master at setting his teams up to defend properly and a point at Anfield is rarely a bad result. However, it seems rather reductive that two managers believed to be among the best in the world both moan because their opponents didn't play into their hands. You'd be forgiven for thinking it's their job to counter such a scenario.
Like those who thought that the office of the US President might magically change the personality of the Donald Trump they saw on the campaign trail, the fact that United are deemed to have an attacking tradition isn't going to alter the approach of Jose Mourinho.
It's not easy to set a team up so brilliantly, but this wasn't Barcelona, Atletico, Real Madrid or even an in-form Manchester City they were playing; it was Liverpool, who had one win in their previous seven games, were without Sadio Mane and had Alberto Moreno at left-back.
At one point during the second-half United had a throw-in on the right wing which made its way to Nemanja Matic. United had three players on the halfway line marking one Liverpool striker, but not only did Matic not even look to his left to switch the play, Matteo Darmian, at left-back, hadn't even moved to give him the option.
A central midfielder of Matic's quality should, instinctively, want to widen the pitch and an impulse to go forward usually grips a full-back when his team have good possession and his central defenders have things under control. It showed how well Mourinho got his message across that both urges were so suppressed.
Mourinho claimed that he had nothing on the bench to change his approach even if he wanted to, but had it been Juan Mata on the ball rather than Matic in that situation, it's likely United would have done something beyond immediately give the ball away and revert into a shape.
Instead, Mata watched from the bench as Jesse Lingard - who is firmly in the Alex Oxlade-Chamberlain bracket of mysterious ability - was chosen to replace Henrikh Mkhitaryan. Why bring on a player who can pass, when you can bring one on who can run?
The flat-track bully approach of battering teams in the lower half of the table may well be enough to push United close to the title, but at some point, if they want to win either the Premier League or Champions League against elite opponents, Mourinho will have to trust himself and his players to do something beyond a counter-attack.
And they'll have to do it against far better teams than the one they faced on Saturday.