Paris Saint. Germain lost their first home game of the season to Stade Rennais 2-0 on Sunday.
PSG leads second-placed Olympique de Marseille by seven points after ending Stade de Reims's 19-game league unbeaten run with a 2-1 away win,
but the capital team was eliminated from the Champions League by Bayern Munich earlier this month and the French Cup by OM in February.
That left just the league title, and Sunday's performance at the Parc des Princes highlighted their weaknesses and placed more pressure on coach Christophe Galtier.
In the absence of Presnel Kimpembe and Marquinhos, their defence struggled and their assault was reduced to Kylian Mbappe.
Rennes, who beat PSG twice this season with goals from Karl Toko Ekambi and Arnaud Kalimuendo,
climbed up to sixth on 50 points from 28 games, 16 behind PSG.
Monaco are fourth on 54 after beating AC Ajaccio 2-0 away earlier Sunday.