Man Utd vs PSG: Kylian Mbappe and Presnel Kimpembe get the goals before Paul Pogba red card

Manchester United 0-2 Paris Saint-Germain: Goals from Kimpembe and the always impressive Mbappe left United requiring a stunning turnaround in Paris

A huge dose of reality for Ole Gunnar Solskaer and an immensely satisfying sense of revenge for Angel Di Maria. That is how quickly an entire mood can change, although it helps when you’ve got someone as quick as Kylian Mbappe.

Either way, there were no such sharp responses from Manchester United - or their manager. Solskjaer and his side reacted inadequately to all of it. A first Champions League test brought his first defeat as manager, after 13 games, as they were ultimately outclassed 2-0 by Paris Saint-Germain.

The French champions and - particularly - Di Maria responded to everything superbly. They capitalised on the loss of United’s pace through injuries to Anthony Martial and Jesse Lingard, and reshaped much better than Solskjaer, with that releasing Di Maria in so many ways.

It turned out that booing, barging and throwing a bottle at the unpopular former United player was entirely the wrong thing to do. It only drew a brilliant response from him, as he offered two assists in the killer goals for Presnel Kimpembe and the electric Mbappe. There’s also the argument that Solskjaer’s tactical decisions actually fed into that.

The Norwegian now has a lot more to think about ahead of a second leg that looks even more daunting.

Really, Di Maria ended up just one of many PSG players who showed so much more experience and nous than United. Thiago Silva, Marco Verratti and Dani Alves ensured the injuries to Edinson Cavani and Neymar never affected them.

It was just another reality check that, against that, Paul Pogba looked more lost than in so many recent games and was eventually sent off. United finished the match an ill-disciplined rabble, pulled all over the place.

PSG had the quality, and class, to pull away from the strangled match it had initially been.

The game had already been a surprisingly scrappy affair with a lot of aggression and spite for two clubs that had never met in a competitive game. It was difficult not to think this was down to one of the few players who has played for both in Di Maria - even if certain people at United would dispute whether his spell there was “competitive” - or that the home players had been told to get stuck into him.

Many of Di Maria’s former teammates felt he couldn’t handle himself when it got tough, something that felt all the more relevant when Young shoulder-barged him in the first half. The Argentine ended up prone under the United support that was so often booing him.

That, judging by what was to come, felt it like it had the adverse effect.

Young was probably fortunate not to be sent off for that, given how he’d previously been booked for taking down Mbappe and how card-happy referee Daniele Orsato was, but then so was eventual goalscorer Kimpembe for another challenge.

Presnel Kimpembe opened the scoring (AFP/Getty)

The one thing you could say for the referee was that the game was so characterised by scrappy challenges that it was difficult to tell them apart and must have been worth some yellow cards, but all it did was further disrupt the flow.

That was only broken by the occasional moments when the many speedy players - most conspicuously Mbappe - suddenly burst up the pitch.

United were robbed of two of theirs at half-time, with Jesse Lingard and Anthony Martial going off, and - much like the treatment of Di Maria - it probably had bigger effect than initially considered.

It was as if PSG suddenly felt freer, more willing to go for it themselves, without the threat of the home side doing them on the break.

The French side scored a second away goal (Getty)

Whatever about the level of the opposition or the stage, though, this is also where the first questions of Solskaer’s tactical mind and decision-making could be asked. United had lost two of their fastest players in what was already a stodgy game, and replaced them with an even stodgier player in Juan Mata and someone who seems to have lost that spark in Alexis Sanchez. There admittedly weren’t many options, but he chose the wrong ones.

PSG were emboldened, and Kimpembe entirely fortunate. Their new assertiveness brought that corner, that saw Di Maria finally deliver here.

His cross was supreme, United’s marking was not and there was Kimpembe - in the box to finish rather than in the dressing room sent off.

Di Maria was set off, visibly roaring obscenities in celebration. He shortly after had that bottle thrown at him, only to lift it up and somewhat passively show the ref. It only saw him lift his game, and show bottle of a different kind.

Kylian Mbappe scored a potentially decisive second (AFP/Getty)

Within moments, PSG had two goals and he had two assists, Mbappe - inevitably - neatly slotting in a supreme cross from the Argentine.

Di Maria was eventually brought off to more boos from the Old Trafford crowd, although they were offset by some applause, and huge cheers from the raucous away end.

Solskjaer now has to come up with a much better response for the return.

It’s going to take much than good feeling, though, to bridge the gap to what just looks a much better PSG side.