Five days after beating Barcelona 4-1 at Camp Nou, Paris Saint-Germain were beaten 2-0 by Monaco in Ligue 1, with the goals coming from Sofiane Diop and Guillermo Maripán, the former Alaves defender.
Mauricio Pochettino's side didn't look a shadow of the team that won so comfortably at Barça.
The defeat sees PSG drift further away from top spot in the French league, leaving them four points behind leaders Lille and one behind second-place Lyon,
Monaco, meanwhile, sit fourth, now just two points behind PSG after beating them on Sunday in Paris.
Nico Kovac's side are on a good run of form and took advantage of the euphoria the win generated to send a message to Barcelona via Twitter.
"We beat PSG at home and away!" the club's Spanish account wrote. "Barcelona, if you need some advice, send us a DM (direct message)."
NEW FC BARCELONA PODCAST IN ENGLISH