I wonder what Laurent Blanc thought of it.

Partly, of course, what Blanc the former PSG boss who lost his job after losing to a comeback win against Manchester City in the Champions League last season, thought of it.

But mostly what Blanc the former World Cup-winning defender thought of it.

‘The President’ would be just as good a defender nowadays, what with the building from the back, and the expectation to play constantly. Being able to defend is a bonus too.

What has happened to the art of defending?

What has happened when a team with a 4-0 lead go into a game, regardless of whether it was Barcelona at the Nou Camp, and produce that — a performance that for all of Barca’s attacking prowess actually saddened those who really love this game.

What happened to the team from Valentine’s Day in Paris who were so bold, so fearless and yet then wilted so heartbreakingly pitifully?

The question has been asked by some whether it was the greatest game of all time, but for it to be the greatest game of all time, it truly takes two to tango.

PSG coach Unai Emery is renowned as a shrewd tactician but surely the obsession with possession has reached its nadir when you see a side camped in their own half, deliberately defending so deep, still trying to play little touch passes through the midfield. Thirty yards from their own goal.

Squeeze up. Push the play. Defend on the front foot. Clear your lines. Get the forward players to run the channels and give the defence a breather. Get Barcelona facing their own goal. You’re not allowed to say this nowadays but, gulp, here we go — go direct if you have to. Ping it diagonally in the corner.

It was a one-off match where PSG only had to defend a four-goal lead and claim a goal at the other end to kill the contest, not a presentation from the Pep Guardiola school of coaching.

Paolo Maldini, Franco Baresi, Fabio Cannavaro, John Terry, Alessandro Costacurta, even Blanc — would any of the truly great defenders have allowed that to happen? It was beyond embarrassing and humiliating for PSG, it was — and is — the kind of result that will scar for years.

Type ‘great football defenders’ into Google and the first three modern suggestions are Sergio Ramos, Gerard Pique and Thiago Silva.

Yes, that Thiago Silva. The PSG defender who was at the opposite end of the park from Pique apart from the last few minutes when the Barcelona centre-back was right beside him as even Barca went old-school. There must be a reason the highest level the Brazilian has played is an average Milan side and then five years in France because the lack of leadership the man with the armband showed on Wednesday was galling.

Ramos skippers Real Madrid and Pique is Barca’s rock because, yes, they can play, but oh so crucially they can defend too.

In the modern era where teams defend from the front and build from the back, Wednesday was a painful example that, at the end of an exhilarating night, nothing can beat being able to do the main purpose of your job properly.

Like Blanc, Emery will lose his job at PSG.

Because the performance his side produced on Wednesday was, quite simply, indefensible.

And finally ...

I’m a fan of Michael Owen but seeing a former Real Madrid player running round the studio in joy when Sergi Roberto scored Barcelona’s incredible winner left me incredulous. File under ‘what has become of the game?’. Mind you, what do you expect from a Liverpool player who went on to play for Manchester United?