The general consensus was that José Mourinho had erred on playing André Schürrle as a false nine on Wednesday night, yet it was after he had gone off to be replaced by Fernando Torres that Paris Saint-Germain scored twice. That's a simplistic way of looking at things, and Torres had barely been on the field when David Luiz conceded a needless free-kick and then put through his own goal to give PSG the lead, but it does tally with Mourinho's post-match claim that Chelsea had "controlled" the game until Torres came on because of the way Schürrle kept "dropping deep".

To say they controlled it might be a stretch, but it is true that, once Chelsea had conceded the first goal, they seemed comfortable for much of the rest of the time Schürrle was on the pitch. This was control in the sense of not-being-troubled-by rather than dominating, even if PSG's weird jitteriness after conceding did make Chelsea seem the more likely side to score in the second half of the first half.

Schürrle managed just 17 passes and no shots in a little under an hour on the pitch, but his impact was in prevention rather than creation and, necessarily, the generation of non-events is far less easy to monitor statistically. What's certainly true is that things did not improve once Torres came on: he had only 12 touches in the whole of his half-hour, misplaced half his passes and didn't manage a shot.

In a sense, the false nine ploy was forced on Mourinho: Samuel Eto'o is injured and he has clearly lost faith in Demba Ba and Torres (particularly problematic given the Spaniard has shown repeatedly he is at his best when he is confident and Mourinho makes little secret of how little regard he has for him, creating a vicious circle in which Torres lives down to his manager's expectations).

Yet those doubts have existed all season, and Mourinho had used Schürrle as a false nine only twice before: in the Super Cup against Bayern Munich and in the league away to Manchester United – back near the start of the season when 0-0 still seemed like a decent result for a top side at Old Trafford. In that regard, using Schürrle in that way, as an auxiliary midfielder, was a mark of the highest respect from Mourinho for PSG – and one their midfield deserves.

It's the midfield three that suggests this PSG side is not just about buying the biggest names, throwing them together and hoping something sticks – even if there has been plenty of that. There is a tremendous balance and flexibility about that central trio and, while the understandably vaunted front three will capture the bulk of the attention, it is in their midfield performances that the key to PSG probably lies. After all, they ended up winning comfortably enough on a night when Zlatan Ibrahimovic was anonymous and Edinson Cavani chugged diligently on the right, doing as much to help nullify Eden Hazard as he did from a creative point of view.

After Chelsea had drawn 2-2 with Juventus in the Champions League last season, Roberto Di Matteo raved about Oscar's performance in shutting down Andrea Pirlo, describing him as "tactically perfect" before eventually getting round to talking about the two goals he'd scored. Oscar appears physically slight, but he is superb as a defensive creator – which is, of course, one of the reasons Mourinho likes him so much. His role last night was to stick to Thiago Motta, looking to prevent him setting the tempo from the back of midfield, the two essentially cancelling each other out – another reason, presumably, that Mourinho felt he needed Schürrle dropping back to become an extra body.

The great strength PSG have, though, is that Marco Verratti is just as adept as Motta at starting moves from deep. He may still suffer the recklessness of youth, as this profile from Tom Williams explains, which perhaps means he is not quite ready yet to be the playmaking fulcrum in a top-class side, but as a spare pivot to be used when Motta is otherwise engaged, who can break forward to support Cavani on the right, he is ideal. Or, at least, he is ideal when his side takes charge of the game: if Chelsea are to get at PSG in the second leg, it will surely come via Hazard attacking Christophe Jallet on the Chelsea left and that will offer a severe examination of Verratti's defensive capacity.

On the left of the three is Blaise Matuidi, who is normally praised for his energy and his aggression, for offering a physical counter-point to the skills of Verratti and Motta. It was his capacity to get forward on the left, though, that created the first two PSG goals, first with the cross that John Terry struggled to clear, and then by drawing the needless foul from David Luiz that led to the free-kick that led to the goal.

And that perhaps hints at the greatest strength of the PSG midfield: it's not just that it's balanced, that there is intelligence, imagination, muscularity and drive; it's that to an extent all three players exhibit sufficient range of capacities to step in for each other as required. It may be Zlatan and Cavani who catch the eye, but Mourinho's use of Schürrle - indeed, Chelsea's need for Schürrle - showed just how potent PSG's midfield has become.