PSG face a real fight to retain their Ligue 1 title after being deservedly beaten 2-0 by a slick Monaco side at the Parc des Princes on Sunday evening.
Goals from Sofiane Diop and Guillermo Maripan in either half sealed what was an assured performance by Niko Kovac's visitors, who controlled the contest and in turn put themselves back into the mix in an exciting title battle.
It was a game in which PSG predictably had most of the ball - well over 70% of possession - but unlike in midweek against Barcelona, PSG seemed toothless and could not create anything like a clear-cut opportunity throughout.
Kylian Mbappe in particular was subdued and with Neymar injured, Mauro Icardi and Moise Kean were unable to pick up the slack, with both of them putting in equally anonymous performances.
As it was, Monaco soaked up PSG's territorial advantage and were largely clinical when chances came their way. Just six minutes were on the clock when Bruno Aguilar's delivery found the head of Diop, who powered the ball into the net.
Monaco retreated into their territory once again and invited PSG to attack them, but were robust in holding back the tide and doubled their advantage five minutes into the second half.
Guillermo Maripan scored his fifth goal since the turn of the year, an amazing return for a defender, pouncing on a loose ball in the area to smash into the net past Keylor Navas.
Kevin Volland missed a good chance to make it three soon after but it proved academic; PSG were lethargic throughout and only mustered a single shot on target in the game.
With this victory, Monaco move to within six points of leaders Lille, who have 58 points, followed by Lyon three points back on 55. PSG have 54 with 12 games remaining in one of the most exciting Ligue 1 title races in years.