With the way he is so willingly talking up the possibility of smashing in six goals against one of Europe’s best sides, it would be difficult to deny Luis Enrique has struck the right tone, as his Barcelona seek to defy history.

The truth, however, is that it’s difficult to know what the right tone is for a second leg like this against Paris Saint-Germain.

There is no precedent whatsoever for what Barcelona are trying to do, no previous examples. Not even Leo Messi has conjured something so seemingly impossible, although he now must try.

No-one in the 62-year history of the European Cup and Champions League has overturned a four-goal deficit from the first leg. Sure, it has happened three times in the other continental competitions, but all of those involved an away goal. None of them meanwhile involved a side as accomplished as Unai Emery’s PSG.

It was all the more impressive then that Luis Enrique was so strident, that he was so successfully making the near-impossible seem possible. He was talking as if this really is on, that it really is not that much of a stretch to think this Barcelona can overturn a 4-0 PSG lead. He was convincing. He made you believe.

Di Maria scored twice against Barcelona (AFP/Getty Images)

“If a team can score four times against us, we can score six times against them. We have seen that before this season. We have nothing to lose.

Reason four hope? Previous four-goal deficits overturned in European competition

“My optimism does not mean I have unbreakable faith, but there are all sorts of performances in sports, negatives and positives. We have not been in a situation like this before, but I have faith in the team. You always have to keep your emotions in check.

“I am not interested in becoming part of history. But I am convinced we will get chances. That does not mean it is definitely going to happen, but I think we can get close and boost morale even further, which could affect our opponents.

“I don’t have the feeling that we need the best game since I got here. We obviously have to play well and really effective. But it depends on how the match goes.”

Enrique is hoping for a miracle (Getty)

That assertiveness, and the convincingly open way that Luis Enrique spoke, is in-keeping with a change in his demeanour over the last few weeks and especially since he announced he would be leaving at the end of the season. It really is as if he has been released, has “nothing to lose” as he put it, and is freer to say what he wants and to try things.

That, of course, has led to a change in Barca too; a new feel to the team. Luis Enrique has tried a new formation in moving to three at the back - a tactical nuance, in truth, that many thought beyond him - and it has seen the team move onto an extra level. Several extra levels, really.

The side that seemed so oddly meek and detached in the first leg now look more ruthless than ever, with more levels to their game again than ever. That has been the effect of the system, and it doesn’t feel unlike the transformation they underwent in the January of the 2014-15 treble season.

Barcelona will need Messi to deliver (Getty)

Certainly, if you were looking to overturn such a deficit, it would be difficult to think of a better set of circumstances suddenly going in your favour: a team featuring Messi, Neymar and Luis Suarez having found a balance that brings them onto greater levels, and poses a new challenge to the opposition that they may not be prepared for.

It’s just that PSG may be among the worst possible opponents, especially with a cup specialist of a coach like Emery. They have undergone their own transformation under the Basque, from a squad struggling under his approach to one now apparently taking their long-awaited next steps at the top level.

Emery is also well aware of how this game will be about managing emotions as much as tactics, of not letting any Barca goals to get at his team and create a doubt that could become crippling.

“Our idea is to play with personality against a great team and just thinking in the continuation of what we did [in first leg], without thinking about the result.”

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That is the unique texture of games like this, when there is such a gap in the score, but also two sides of such quality. Barca scoring early to make it 4-1, for example, would not be the kind of regular occurrence in an open game that would happen if it were just 1-1. It would instead feel like the start of something deeper, of their attempts to reel PSG in, with that occupying a momentum all of its own.

That is when a healthy advantage can become a mental disadvantage, when the score becomes something you dwell on and try to protect rather than something that offers security and assurance.

Barca have an assurance themselves. They have an opportunity to make history. They have an opportunity to do something truly unique, even for a player like Messi.