Mbappé led the line for 90 minutes as 2019/20 finalists PSG were edged 2-1 in the first leg last Wednesday - Marquinhos's opener cancelled out by Kevin De Bruyne and Riyad Mahrez goals - but he wasn't in the squad for the Lens game due to a calf complaint.

The French World Cup-winner has plundered 37 goals and 10 assists in all competitions this season at a rate of one every 72 minutes he has played, and his presence will be crucial as Paris go in search of the two goals that would send them into a second successive European showpiece. Pochettino remains upbeat.

"Will Mbappe be there? I'm optimistic," he said after the Lens victory, which saw his side regain top spot in Ligue 1 Uber Eats for a matter of hours before LOSC's 2-0 win over OGC Nice. "We think he'll be there. W'll see how it evolves tomorrow and decide before the game.

Watch: All of Mbappé's goals until the mid-point of the season

"He received a blow that could have happened at any time during the match. It can happen. It's not a serious problem but it created a muscle imbalance in his calf."

Lens were perhaps not the ideal opponents for PSG in between the two legs of their Champions League semi-final. Le Sang et Or have European ambitions of their own this season and had gone 13 games undefeated before Saturday's clash. Pochettino was quick to pay tribute to them.

"It was a very difficult game. Lens play good football.," he said. "I really like their play. We struggled, but we deserved to win. We had to dig deep for this victory."

"The 13-game unbeaten streak proves our consistency," said Pochettino's opposite number Franck Haise. "And, despite the defeat, we showed our progress in this game. When we're fifth with four games to go, you can say we have our strengths."