Monaco secured an impressive 3-1 victory over league leaders PSG, who were without a number of their first team stars.
A Paris Saint-Germain side missing the injured Lionel Messi and Kylian Mbappe and hit by a stomach bug warmed up for their Champions League last-16 first leg against Bayern Munich by going down to a 3-1 defeat at Monaco in Ligue 1 on Saturday, their second defeat in four days.
All the goals came in the first half at the Stade Louis II, with Aleksandr Golovin putting Monaco ahead inside four minutes and Wissam Ben Yedder doubling the home side's lead.
The 16-year-old Warren Zaire-Emery pulled one back for PSG but Ben Yedder scored his second of the game, and 19th of the season, to make it 3-1 in first-half stoppage time.
PSG remain top of the table, seven points ahead of a Monaco side who are up to second, but Marseille can close to within five points of the leaders with a win at Clermont later.
PSG will be without Mbappe, their top scorer, due to a thigh injury for the clash with Bayern at the Parc des Princes on Tuesday and Galtier must hope that Messi recovers in time from the hamstring complaint that prevented him from travelling to the principality.