There were only six goals in the four Champions League quarter-final first legs this week, but every game was fascinating in its own way.
Tottenham, Manchester United, and Ajax were particularly impressive from a tactical perspective and yet only one of these teams won, while Liverpool eased past Porto in the only tie that has, perhaps, already been settled.
Here are five tactical points you may have missed from the European encounters...
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Solskjaer blunts Barca but Man Utd lack killer instinct
One brilliant Lionel Messi pass in the 12th minute is arguably the only reason we were not celebrating a superb Man Utd performance on Wednesday.
Ole Gunnar Solskjaer’s 3-5-2 formation proved to be the perfect way to limit Barcelona’s attackers and probe – though cautiously – with their pace up front.
Following a nervy opening 20 minutes, using a back five allowed the United wing-backs to meet the Barca full-backs (the only opposition players providing width) as Luis Suarez was completely isolated against three centre-backs.
Philippe Coutinho and Messi played very narrowly, and so Solskjaer’s decision to pack the middle with bodies was vindicated.
Scott McTominay and Fred were outstanding, constantly first to the ball and controlling Barca’s midfield three with ease.
Paul Pogba pressed high at the tip of midfield to create a front three with Romelu Lukaku and Marcus Rashford, who together pressed high up the pitch to put an error-prone Sergio Busquets under pressure.
This shape stopped Barca from building out, leading to Messi getting drowned out by Fred and McTominay.
However, United just could not find the final pass to create goalscoring opportunities, while that one understandable lapse of concentration from Luke Shaw given his unfamiliar position ultimately cost the hosts.
Pochettino's pressing game pins Pep back
Mauricio Pochettino masterminded what was surely Tottenham’s best performance in Europe since the 3-1 victory over Real Madrid in November 2017, with his brave and aggressive press paying off as Man City were kept at arms’ length in the Tottenham Hotspur Stadium.
The most impressive feature was their timed pressing. They sat in formation 10 yards off the City centre-backs for long periods, engaging only on heavy touches to capitalise on any nervousness.
Harry Kane, Son Heung-min, and Christian Eriksen blocked the passing lanes for City’s back four while Dele Alli followed Fernandinho around the pitch, which meant the visitors just could not get a grip on the game.
Pep Guardiola’s side need possession to grind "big six" teams into submission, but on Tuesday they just could not find a way to turn on the ball or thread it towards their front four.
In attack, Spurs focused on long switches of play wherever possible, which meant dragging players to one side before (mostly Kane’s) cross-field passes could isolate one of the City full-backs.
It was clear that Fabian Delph and Danilo were City’s weakest players, and it was no surprise to see the hosts target both of them; Son versus Delph, a mismatch Spurs tried to exploit all game, eventually forced the breakthrough.
Guardiola's cagey calls cause City headaches
Although Spurs’ shape made it difficult, Man City did not do enough to find a way to outmanoeuvre the press on yet another Champions League night when Pep Guardiola could be accused of overthinking.
His desperation to win the competition has seen the Catalan make unusual tactical decisions in the latter stages and, on Tuesday, City were more defensive than at any point this season – a situation best captured in Guardiola’s decision to pick Ilkay Gundogan over Kevin De Bruyne.
City had beaten Spurs three times in a row, scoring seven in two games before a 1-0 win in October that could have been five or six, and yet Guardiola appeared scared on Tuesday, using two deeper midfielders in an unfamiliar 4-2-3-1 while instructing both full-backs to stay deep.
Together, these features allowed Spurs’ high block to work, since City had fewer options for creating space; David Silva, Sergio Aguero, and Raheem Sterling were trapped behind the Spurs midfield.
What’s more, playing Riyad Mahrez only further narrowed the pitch and allowed Spurs’ left-back Danny Rose to dominate that flank.
Starting De Bruyne and playing their usual attacking game would have given City a tactical and psychological advantage, penning Spurs back with their superior individual quality. Instead, Guardiola’s nervous hesitancy infected his players.
Ajax energy exposes Juve's Can-dependency
Not unlike the first leg of their last-16 tie against Real Madrid, Ajax will be kicking themselves for failing to beat Juventus.
They were superb again on Wednesday, dominating possession (61 per cent) as Frenkie de Jong controlled the game in midfield.
Ajax’s high energy football, with quick one-twos and constant movement, forced Massimiliano Allegri’s side into a hunched 4-4-2 shape for long periods – but the Dutch side just could not get it right in the final third.
Juve clearly missed Emre Can, the man who tends to link play for the Bianconeri by dropping deep and starting moves.
Without him, Ajax’s high pressing successfully stopped Juve from building out from the back. Cristiano Ronaldo’s goal, against the run of play, leaves them in a commanding position regardless, although Ajax will be quietly confident they can repeat Wednesday’s display in Turin.
The other tactical point of note from this match was Ajax’s focus on their left, where David Neres scored the equaliser at the beginning of the second half.
Nicolas Tagliafico’s overlapping runs were dangerous throughout, with Joao Cancelo only just managing to deal with Ajax’s pressure down his side of the pitch.
Porto experimenting only aides Liverpool's cause
Nobody expected Porto to play a 3-4-3/5-4-1 formation at Anfield on Tuesday, which is why the Liverpool forwards deserve credit for adapting quickly to the situation and making use of the spaces that inevitably developed between Porto’s wing-backs and centre-backs.
Liverpool’s counter-press was very effective in slipping Sadio Mane and Mohamed Salah into these gaps, which generally always appear for clubs that are only temporarily deploying such a complex formation.
Both of the hosts’ goals came via the flanks, the first seeing Mane breaking into acres of space on the left before the ball was eventually worked to Naby Keita, and the second a through ball from Jordan Henderson – which split between the left wing-back and left centre-back.
Porto were arguably still correct to play with five at the back, such is the difference in quality between the two sides. The second leg will likely follow a similar pattern, ensuring Liverpool ease into the final four.