The Italian came out to challenge Wilfried Singo in the Ligue 1 clash, and the Ivorian striker's studs ended up raking down the goalkeeper's face.
Donnarumma required treatment before walking off covered in blood in the 22nd minute of the match.
Rather incredibly, Singo, who was already on a booking, avoided a second yellow as referee Francois Letexier deemed the collision accidental.
Donnarumma was then pictured with his face stapled back together in gruesome style.
RMC Sport claim that despite the trauma, he emerged in the tunnel at half time to await an explanation from the referee.
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There was more bad news to come for PSG, who had ended the half 1-0 ahead thanks to Desire Doue.
Eliesse Ben Seghir would then equalise for Monaco, before Breel Embolo made it 2-1.
Ousmane Dembele then levelled things up in the 64th minute before Gonaclo Ramos' winner, but it marked another poor showing for the French giants who have been all over the shop since Kylian Mbappe's summer departure.
Luis Enrique's side are facing a rare title challenge from Monaco and Marseille due to their poor form, and in Europe, where things really matter, the picture is even more bleak.
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PSG currently sit 25th in the league phase of the Champions League, a position which would leave them out of the knockout round of the tournament.
Luis Enrique has baffled with many of his team selections and has reportedly left players bemused by only revealing his line-ups an hour before kick-off.
The European treble winner has also gone to war with underperforming forwards Dembele and Randal Kolo Muani, while Donnarumma has also faced his ire.
The Italian has been benched on three occasions so far this season, with Russian Matvey Safonov stepping in for their biggest game of the campaign so far away at Bayern Munich where they lost 1-0.