Lionel Messi, Neymar and Kylian Mbappe haven't been able to stop Paris Saint-Germain losing 1-0 at Rennes for a second straight away defeat in the French league, and their lead over second-placed Lens is now just three points.
PSG started on Sunday with Messi and Neymar in attack before bringing on Mbappe -- top scorer at the World Cup in Qatar -- early in the second half but still managed only one shot on target in the whole game under driving rain.
Rennes defender Hamari Traore showed how to finish in the 65th minute with a crisp low shot past Gianluigi Donnarumma into the bottom right corner.
Messi sent Mbappe clean through moments later but he decided against curling the ball past goalkeeper Steve Mandanda, and instead fired over on his 200th league appearance.
PSG looked devoid of ideas as they chased the game and, just like when they lost to Lens 3-1 on New Year's Day, were dominated physically and lost most of the second balls.
Neymar was anonymous for most of the game, becoming more visible near the end to argue with Rennes defenders when it was too late.
The Brittany side again proved a tough opponent, having beaten PSG to win the French Cup in 2019 and defeating them at home 2-0 last season.
"The images will speak for themselves," PSG coach Christophe Galtier said.
"We knew we were in for a difficult game and so it proved ... Rennes was far too comfortable in defence."
Rennes stayed in fifth place because they needed to win by two goals to reclaim fourth on goal difference from Monaco.
Earlier, striker Wissam Ben Yedder scored a 14-minute hat-trick as the principality club routed Ajaccio 7-1.
Monaco opened the scoring in the second minute through central defender Axel Disasi and Ajaccio were 2-0 down when midfielder Krepin Diatta tapped in.
Youcef Belaili replied for Ajaccio, but Ben Yedder scored in the 21st and 28th minutes with neat finishes before completing his second treble of the season with a penalty in the 35th.
Substitute forward Breel Embolo added two late goals.
Troyes' Australian coach Patrick Kisnorbo suffered his heaviest defeat since taking over.
Lille strikers Jonathan David and Mohamed Bayo each scored twice in a 5-1 win.
David, who played for Canada at the World Cup, took his league tally to 12 goals -- one behind Mbappe in the scoring charts.
Elsewhere, Montpellier finished with nine players in a 3-0 home loss to Nantes.
Following a 6-1 midweek defeat at Nice, Montpellier's angry fans let their feelings known by throwing flares onto the field early in the game. It was temporarily suspended as the referee led players off and started again 15 minutes later.
Last-placed Angers lost 2-1 at home to Clermont, Toulouse drew 1-1 at home to struggling Brest and Reims drew 0-0 with Nice.