Coach Luis Enrique has slashed Mbappe’s minutes in recent weeks after the player told the club he would leave at the end of the season, but the France captain proved he will be vital if PSG are to finally win the competition for the first time.
The electric Mbappe was impossible for Real Sociedad to shackle and his strikes after 15 and 56 minutes left the Ligue 1 leaders with a simple night in the north of Spain.
Heavily linked to Real Madrid, the determined Mbappe gave La Liga’s defences a glimpse of what horrors may await them next season.
The forward fired over in the opening stages and then blazed past Hamari Traore to set up Bradley Barcola, but Alex Remiro denied him from point-blank range.
It was not so much that Real Sociedad did not heed the warning but simply could not stop him.
Played into the box but wide of goal, Mbappe produced the opener from thin air.
With a couple of clever touches he sent Igor Zubeldia scrambling and opened up enough space for a shot, which he whipped into the far corner from a tight angle.
Mbappe’s vicious strike pulled part of the netting away from the post and players had to wait until it was fixed for play to resume.
They might not have bothered — the contest was effectively over.
Mbappe stretched PSG’s lead 11 minutes into the second half, racing in behind the defence from the halfway line.
The striker shaped another shot to the far post but then tricked Remiro by sweeping home at the near for his sixth goal in eight Champions League matches this season.