Substitute Dennis Appiah inadvertently put the ball in his own net when Nantes played PSG on Saturday.
The French-born Ghanaian diverted the ball over his goalkeeper into the net as PSG secured a 3-1 victory and extended their lead at the top of French Ligue 1.
Lionel Messi grabbed the third goal for the French giants, his first league goal since joining PSG in the summer.
It looked set to be a routine affair after PSG dominated the first half, buoyed by Mbappe's second-minute opener.
The second half saw PSG goalkeeper Navas sent off and Nantes took advantage by drawing level through forward Muani.
But Appiah's interception of a Messi pass looped over goalkeeper Lafont from 20 yards before the former Barcelona playmaker sealed victory.
Appiah was introduced in the 42nd minute for his 11th league appearance of the season.