Mbappe was the star of the show in last month's Champions League meeting between Barcelona and PSG despite Koeman using interesting measures to send a warning to his players.
If Ronald Koeman felt he was motivating his Barcelona players ahead of their clash with PSG at the Nou Camp, his efforts to do so backfired tremendously.
His side were given a thumping in the Champions League last-16 first leg last month as Kylian Mbappe fired home a sublime hat-trick to virtually put the French side into the next round.
There was little Barcelona's players could do as the 22-year-old ran riot, even though Koeman had made it clear - not that he really needed to just who was PSG's dangerman.
As according to L'Equipe , Koeman had attempted to stir up his troops by sticking a photo of Mbappe up in the home dressing room for his players to look at ahead of them facing who he described as Barca's 'number one enemy'.
Koeman will have been fairly happy with the way his side dealt with the threat in the opening half hour, taking the lead through a Lionel Messi penalty.
But if there was any doubt who the key player on the field was, Mbappe soon had his say, scoring the equaliser minutes later before firing PSG in front in the second half and rounding off the victory with his third strike late on as he curled the ball into the top corner after a thrilling breakaway.
Speaking after the match though Barca's boss made no excuses, as he said as quoted by Sports Central: "Surely the result reflects how superior they have been. In the second half we had problems defensively. They proved physically to be very superior to us. "We have to admit that they have been superior. They have shown that they have a more complete team than us. "A 4-1 defeat is normally very difficult. I can lie to you but losing at home 4-1 there are very few options. "The game has shown us that we lack things to be at the best level, especially at the Champions League level.
Mbappe was kept a little more under wraps in the second leg though still scored from the penalty spot before Messi's equaliser saw the sides draw on the night as Barca crashed out of the competition with barely a whimper.
PSG are now bidding to seal their path to the semi-finals as they travel to Bayern Munich on Wednesday in the first leg of the last eight tie.
Think Bayern boss Hansi Flick will probably be keeping any photos firmly in their usual place..