Mbappe scores last-minute winner as PSG bounce back from exit
PSG have been left with just the Ligue 1 title to play for in the remaining months of the season after the Qatar-owned club were knocked out of Europe's elite club competition in the last 16 with a 3-0 aggregate defeat.
They took the lead on their trip to Brittany in the 37th minute when Carlos Soler followed in to score after Mbappe's shot had been parried by Brest goalkeeper Marco Bizot.
Yet the home side, battling to avoid relegation, drew level before half-time through Franck Honorat and it looked like they would hold on for a precious point in their fight to avoid relegation.
But then Mbappe, who had just been booked for kicking Brest midfielder Haris Belkebla in the back of the calf, was sent through on goal by Lionel Messi and rounded Bizot to score.
Despite an unconvincing performance, the result allows PSG to extend their lead at the top of Ligue 1 to 11 points over nearest challengers Marseille, who face Strasbourg on Sunday.