Thomas Tuchel insists Kylian Mbappe cannot be expected to fill the roles of Neymar and Edinson Cavani when Paris Saint-Germain face Manchester United.

The Ligue 1 leaders visit Old Trafford on Tuesday for the first leg of the much-anticipated Champions League last-16 tie, but will do so without Neymar and Cavani, who are sidelined with respective foot and hip injuries.

France star Mbappe is therefore likely to be PSG's main hope of ensuring they leave England with at least an away goal to take back to Parc des Princes for the second leg on March 6.

But head coach Tuchel does not want the 20-year-old to alter his game to compensate for the absence of his usual attacking partners.

"There's no point putting pressure on Mbappe," he told a news conference on Monday. "It's not his job to replace Neymar and Cavani and do the job of all three of them. 

"He has to play freely. I want us to be able to help him with good passes. He's here to grow and this is the perfect moment for that."

Tuchel admits PSG will inevitably be worse off without Neymar, who damaged a metatarsal during a Coupe de France match last month - the same bone he broke last year.

"Let me put it another way: will Manchester United miss [Paul] Pogba, if he was not there? Will they miss [Marcus] Rashford? Of course they will," Tuchel said when asked if his PSG could replace the Brazil star.

"You cannot replace quality players like this. Neymar is one of the key, key players in Europe and we miss him a lot."

Tuchel is particularly wary of the threat posed by Pogba and Anthony Martial, who between them scored all three goals in United's 3-0 Premier League victory over Fulham on Saturday.

"I don't think there's any surprise Pogba is key," he said. "He's an incredible player with wonderful qualities. He's extremely strong with the ball at his feet. I think he's always dangerous offensively. Him and Martial are a dangerous pairing."

However, Tuchel intends to set his team up to attack United and hopes to score at least once.

"We have our identity and it's not easy to change a team's identity. We play attacking football - it's in our DNA," he said. "We're here to score, maybe more than one.

"I imagine United will be bold and we'll have to be at our best level. I'm sure there will be times tomorrow where we'll be defending deeply. 

"Over 180 minutes, I'd say it's a 50-50 game. At Old Trafford, I'm not sure. We have a second leg in Paris, and we feel very strong and comfortable at Parc des Princes. It's one of these games where the details, you can get a decision from the referee, a yellow, red, anything can make the difference. It's a close game."