Kylian Mbappe's importance to Paris Saint-Germain was all too evident long before his stoppage-time strike gave PSG a narrow win over Real Madrid in the first leg of their Champions League showdown on Tuesday.

It is understood that PSG rejected an offer worth up to 180 million euros ($204m) from Madrid in August for Mbappe, despite the France World Cup-winning striker being in the final year of his contract.

PSG wanted at least one more season with Mbappe at Parc des Princes, knowing that－even with Lionel Messi and Neymar there too－he is the man it needs if it is finally to win a first Champions League title since the Qatari takeover of 2011.

Mbappe is still expected to leave at the end of the campaign for Madrid, the club which has tracked him since he was a teenager but which is now in danger of going out of the Champions League after his last-gasp winner.

The last-16 first leg in the French capital was still goalless in the fourth and final minute of injury time when the 23-year-old Mbappe burst into the box and finished through the legs of Madrid goalkeeper Thibaut Courtois.

That gave PSG a 1-0 victory that even Madrid coach Carlo Ancelotti admitted was deserved after a game dominated by the home side.

Mbappe had the Ligue 1 leader's best chance of the first half and forced a good save from Courtois early in the second half before winning a penalty just past the hour mark when he was fouled by Dani Carvajal.

Messi took the spot-kick only for Courtois to save, but Mbappe kept tormenting the Real defense and eventually got his reward, underlining why the Spanish giant is so desperate to secure his signature.

"I have been working with him for just over a year now and you could see tonight just how good a player he is," said PSG coach Mauricio Pochettino.

Ancelotti described him as "unstoppable" and Real risks being exposed by his terrifying pace on the break as it chases the tie in the return match on March 10.

Speculation swirls

Mbappe's late strike against Real came four days after he also scored a last-minute winner in a Ligue 1 game against Rennes.

He now has 22 goals this season in all competitions, while PSG's second-top scorer is Messi with seven.

Indeed Mbappe－Ligue 1's top scorer in the last three seasons－has four more goals than Messi, Mauro Icardi, Angel Di Maria and Neymar combined in the current campaign.

For all the outstanding talent around him, he is the man who makes the difference and PSG's Qatari president, Nasser al-Khelaifi, can only hope a victory in the tie might persuade the one-time Monaco prodigy to sign a new contract at the club.

"Too many questions are asked and too many things are said," Mbappe insisted when asked about the ongoing speculation over his future.

"The truth is that we are talking about Paris Saint-Germain and Real Madrid, two big clubs. I am a PSG player and I am still really happy.

"I said I would give everything here. I had to come out and prove it. I did it this first time and now I need to do it a second time at the Bernabeu."

In contrast, Messi is struggling to reproduce his Barcelona form and he failed from the spot.

The Argentine, who won his seventh Ballon d'Or last year, has missed five of the 23 penalties he has taken in the Champions League.

He has scored just twice in Ligue 1 this season and two of his five Champions League goals so far came in an inconsequential group game against Club Brugge.

Meanwhile, Neymar made his return as a substitute after two and a half months out with an ankle injury and helped set up Mbappe's late goal with a crafty backheel.

There should be plenty more to come from the world's most expensive player if he can just stay fit, but Mbappe holds the key to European glory, and both PSG and Real know it.

AFP