Having missed his side's previous match with an ankle problem, Mbappe scored at the back post after a corner.

Bradley Barcola added the second with a lovely finish past Alex Remiro.

Real Sociedad keeper Remiro had earlier denied Mbappe a second when he tipped his attempt on to the crossbar.

PSG, who have never won the Champions League, were far from their best in the first half and Real Sociedad's Mikel Merino hit the bar just before half-time.

"If you told me at half-time we would win 2-0, I would be dancing for two hours," PSG manager Luis Enrique told TNT Sports.

"We had to change everything because they were pressing us very high. We couldn't press and it was like a nightmare.

"When that happens you are going to lose confidence, but football is unbelievable and we could change that. In the second half it was more what we wanted."

Real Sociedad will believe they can turn it around in the second leg in Spain on 5 March, but will have to offer a much more attacking threat than in Paris.

Mbappe ignores speculation to carry on scoring

Qatar-owned PSG have spent vast sums on transfer fees and wages in recent years only to be eliminated from the last 16 of the Champions League five times in the past seven seasons.

They have won nine Ligue 1 titles since Qatar Sports Investments took over in 2011 but, with European success eluding the club, they have also appointed seven managers in that time - four of those in the past four years.

Enrique, their latest manager who steered Barcelona to Champions League glory in 2014-15, returns to Spain for the second leg in three weeks' time knowing his team are in a strong position to advance thanks partly to Mbappe.

With the forward's contract running out at the end of June there has been much speculation about his future, but to his credit the 2018 World Cup winner with France has delivered goals all season.

Mbappe has been directly involved in 38 in 30 appearances for his club this season - 31 goals, seven assists - the most of any player in Europe's big five leagues.

In addition, he has now scored 44 times in 68 Champions League appearances for Monaco and PSG.

In January Mbappe, who has been linked with Real Madrid, said he had not made a decision about his future and it remains to be seen where he will be playing his football next season.

His performance against Real Sociedad illustrated what a huge asset he is to PSG, with four of his seven attempts on target.

He would have walked away with the match ball but for Remiro, who denied Mbappe as early as the sixth minute after he was played in with only the keeper to beat.

Bradley Barcola, 21, was one of three players in Paris St-Germain's starting XI aged 21 or under - also Warren Zaire-Emery, 17, and Lucas Beraldo, 20

Real Sociedad fade after bright start

This was Real Sociedad's first knockout tie in the competition for 20 years.

It appeared to be going to plan for the team from the Basque Country as they limited PSG to a handful of chances in the first half, before conceding twice in the space of 12 minutes.

The absence of captain Mikel Oyarzabal because of injury was a blow, and manager Imanol Alguacil will hope his leading goalscorer is fit to play in the return leg.

Real Sociedad conceded as many goals in the French capital as they did in the entire group stage - two in six games - while this was their first defeat in European competition since March 2023, ending a seven-match unbeaten run.

"Two goals is nothing, and at home, with our fans pushing as we have done in the last games in the Champions League, I think we have a chance," said former Newcastle midfielder Merino about his side's hopes of turning the match around in the second leg.

"It's all about being efficient, about scoring goals, which is what we haven't done lately but we know that with our fans we can do it."

Real Sociedad keeper Alex Remiro saved four of Paris St-Germain's six attempts on target