Nancy climbed off the foot of the Ligue 1 table on Sunday with a shock 1-0 win at 10-man Marseille, while former Romanian international Adrian Mutu scored twice as Ajaccio upset seven-time champions Lyon 3-1.
The results capped a memorable few days for Paris Saint-Germain, who own a three-point lead over Lyon at the top following their 4-0 dismantling of Toulouse on Friday that was fuelled by Zlatan Ibrahimovic's league leading 20th goal of the season.
Meanwhile, Marseille are now six points adrift of the leaders following their surprise defeat at Stade Velodrome.
Paul Alo'o Efoulou almost handed Nancy an unlikely lead when his acrobatic volley was cleared off the line by Andre-Pierre Gignac.
The Cameroon striker was then thwarted by a sharp save from goalkeeper Steve Mandanda just before half-time.
With Nancy belying their status as the division's bottom club, their cause was further helped when English midfielder Joey Barton was dismissed on the hour-mark after collecting two yellow cards in the space of five minutes.
"I'm very disappointed, I had a role to play in the defeat. I have to apologise to the team," said Barton, referring to his sending off.
Patrick Gabriel's men duly capitalised on their numerical advantage 13 minutes later when Romain Grange's inswinging corner was flicked on by Salif Sane with Andre Ayew making a mess of an attempted goalline clearance.
Gignac squandered a late chance to draw Marseille level as he was unable to get the ball out of his feet with the goal at his mercy as Nancy secured just a third win of the season and their second in as many outings.
Mutu brace downs Lyon
Earlier, France under-21 striker Alexandre Lacazette volleyed Lyon in front on 53 minutes at Ajaccio but they could only protect their advantage for four minutes before their relegation-threatened rivals levelled the match.
Moroccan international Chakhir Belghazouani pounced on a loose ball in the box and fired past an unprepared Remy Vercoutre in the Lyon goal for the equaliser.
It was then left to Mutu, the former Chelsea, Juventus and Fiorentina star, who has endured a troubled career before surprisingly signing with Ajaccio in the off-season, to roll back the years with two late strikes.
A confident header on 65 minutes from a Johan Cavalli cross put the home side in front.
Lyon were then awarded an 87th-minute penalty, but Guillermo Ochoa was the hero as he turned away Bafetimbi Gomis' spot-kick.
And Mutu assured the islanders of victory in stoppage time as the 34-year-old tucked away his seventh goal of the season after Dejan Lovren was sent off for bringing down Dennis Oliech in the box.
"We knew that this Lyon team were very dangerous and they might open the scoring in the first 20 minutes," said Ajaccio coach Albert Emon.
"Our objective in the first-half was to contain them which is exactly what we did. We gave up a goal early in the second half and that completely liberated us. We came back and there was some real suspense at the end."
Defending champions Montpellier came from a goal down to beat Brest 3-1.
Gaetan Courtet gave the visitors a 33rd-minute lead at Stade de la Mosson but Montpellier answered with goals from Souleymane Camara, Marco Estrada and Younes Belhanda.