Changing the shape of your side for a big game will always draw attention. So Arne Slot put himself in the spotlight by setting up Liverpool with a back five against the champions of Europe.

The result - a 2-0 defeat by Paris St-Germain in the first leg of their Champions League quarter-final - left Liverpool's season hanging by a thread.

It was a surprising tweak. The only other time Liverpool have fielded a back five this season was in their Carabao Cup fourth-round defeat by Crystal Palace in October.

So why make that change? Did Slot get his tactics wrong? Or were PSG just too good?

In Wednesday's match, PSG had 74% of the ball and 18 shots to Liverpool's three. These stats are damning but Liverpool didn't set up to defend their own box for 90 minutes, despite starting with a back five.

Out of possession, they looked to press high - albeit without much success. Hugo Ekitike, Dominik Szoboszlai and Florian Wirtz formed a narrow line between PSG's defence and midfield. PSG dropped one of their midfielders back, forming a makeshift back three with the two central defenders.

Liverpool's front three went man-to-man with these three players. Behind them were the remaining two PSG midfielders, who were marked by Liverpool's midfield duo. Liverpool's wing-backs were tasked with marking Achraf Hakimi and Nuno Mendes.

PSG rotated impressively to find players unmarked. Full-backs Hakimi and Mendes both pushed high up the pitch, pinning back Liverpool's wing-backs. This prevented Liverpool having any presence in wide areas when they pressed.

With Liverpool's midfield two marking PSG's central midfielders, they were unable to pull into these wide areas either.

The French side dropped their attackers deep, into these empty wide positions with Liverpool's back three reluctant to follow them out into these areas.

"I thought we could try and press them really high and aggressive," Slot said. "Every time we tried to press them high and aggressive, those were the moments we got ripped apart."

On the night, Liverpool's centre-backs were tasked with backing up the press when the players ahead of the ball applied pressure.

Ibrahima Konate, on the right, carried out these instructions throughout the game in support of Jeremie Frimpong - but the distances he ended up having to cover in an unfamiliar role left him exposed.

If he was slow to react, PSG would drop an attacker deep, who could then get on the ball, turn and drive at the defence, with space between him and an out-of-position Konate.

At times, Liverpool executed the press well, with their front three blocking PSG's makeshift back three - before Frimpong jumped up to press whichever home player had rotated to the left side of defence.

PSG, however, adapted to this. The players in full-back areas took up deeper positions, increasing the distance Liverpool's wing-backs had to cover when pressing.

When Frimpong did press, it was Konate's job to follow his man.

But with time on the ball, PSG began to play over the top, taking advantage of the spaces behind Konate, forcing 34-year-old Virgil van Dijk across from the centre.

A good example of this early on was seen in Hakimi's run from right-back to the left wing. Milos Kerkez, a natural left-back, tasked with marking him, likely felt uncomfortable moving to the other side of the pitch before Mendes played a long ball over Konate to find Hakimi unmarked.

As the game progressed, PSG were able to establish dominance in Liverpool's third. With Liverpool firmly in a back five at this point, the PSG attackers cleverly used unorthodox movements that made the game difficult for Van Dijk.

PSG's fluid attackers either dropped deep or moved to one side of the pitch, creating overloads around Liverpool's midfield.

Following the match, the Liverpool captain highlighted PSG's movement, saying: "It's what they do, isn't it? They move around everywhere and we have to communicate well and follow our man. And take the risk in that sense."

Konate did track his winger everywhere - which explains why he was seen defending on the right flank at times. Van Dijk largely stayed in the middle of the defence, venturing out less often than his defensive partner.

The free-roaming Ousmane Dembele didn't engage much with Van Dijk and was often seen on the left side of the pitch, leaving the Dutch defender without an attacker to pick up.

In the build-up to PSG's second goal, Dembele left the attacking line and picked up an unusual position in central midfield. Van Dijk moved over slightly before gesturing to Alexis Mac Allister to pick him up. While this occupied Van Dijk, PSG created a chance that led to their second goal, scored by Khvicha Kvaratskhelia.

Joao Neves, Kvaratskhelia and Mendes ended up on the left flank in close proximity - an asymmetrical set-up intended to perplex Liverpool.

Right wing-back Frimpong pressed Neves on the touchline, while right centre-back Konate marked Mendes, the spare man who then dragged him out of position. Kvaratskhelia made a run from deep into the space Konate vacated.

The distance between Konate and centre-back Van Dijk here was big partly thanks to Dembele's role off the ball. That ultimately prevented Van Dijk from being able to come across to defend against goalscorer Kvaratskhelia.

Luis Enrique's PSG are one of the most impressive sides in world football. In this kind of form, they would probably have found a way to win whether Liverpool set up in a back four or back five.

Although Liverpool did end up having more bodies around their own box, their press was ineffective, meaning they conceded control of the ball and ultimately the game.

The first leg was a clear mismatch but Slot and his players still have a chance to take the lessons learned and put things right in next Tuesday's second leg at Anfield.