Now the Parisiens can no longer be so confident of progressing.

"Over 180 minutes I would say it's 50-50," Tuchel said through a translator. "Tomorrow, with them at home at Old Trafford whether it's 50-50 I'm not sure but we have a second leg in Paris where we are strong and comfortable.

"At this level it's the details. It could be a decision of a referee, a yellow or a red that can make the difference. It's a close game."

Tuchel said he never got as far as scouting Mourinho's United, but he is clear about the challenge posed by the Solskjaer version – still unbeaten with 10 wins from 11.

"They play with a lot of confidence, they score a lot of goals and get a lot of early leads," he said. "It's an impressive run. To play at Old Trafford in this moment against this Manchester United is one of the toughest challenges you can have."

And it is a challenge which only got harder for PSG at the weekend, when Cavani injured his hip after scoring in a 1-0 win over Bordeaux. Neymar has been missing since breaking a metatarsal on January 23 and faces 10 weeks out.

"Would Man Utd miss (Paul) Pogba or (Marcus) Rashford? Of course," Tuchel said. "Neymar is one of our best players and one of the best players in Europe. We will miss him a lot. And now Cavani is out."

But Tuchel said their absence should not change the way PSG play, particularly given they still have one of the best strikers in Europe in their side in the form of Kylian Mbappe.

"Obviously we're going to be missing a couple of key attackers, but you don't change your identity for that reason," Tuchel said.

"We have a tradition, we play attacking football and that is how we're used to playing – to create chances.

"It's in our DNA. That's how we play. To change it is really difficult."

However, Tuchel did say some things about his side have changed – particularly in terms of maturity since their 3-2 defeat to Liverpool early in the Champions League campaign.

"Absolutely, otherwise we wouldn't have been able to draw the game against Napoli under a lot of pressure, nor beat Liverpool in what was a decisive game for us," he said.

"I think we've come a long way. We're a really tight-knit team with a lot of energy.

"We cannot forget the fact we're a big club, we are from Paris, the capital of France. We are capable of playing at the highest level but we don't have a lot of history in the Champions League.

"We haven't played a lot of finals or semi-finals so sometimes it is difficult for us to play Liverpool or Manchester United. There is an energy for these clubs and I believe it really makes it more difficult. That is why we must stay together."

There will be a familiar face in the PSG side with Angel Di Maria set to return to Old Trafford, where his career failed to fire, and Julian Draxler revealed his team-mate was fired up.

"I was asking him some questions about Manchester United," said Draxler. "I won't tell you what he said, but he will be ready.

"He's a big player. He has a lot of respect for the club, there was nothing terrible in what he said, but it was between me and him."

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