An own goal by Mamadou Sakho and a Pierre-Emerick Aubameyang strike saw St. Etienne inflict a first defeat of the season on Paris St. Germain with the Ligue 1 leaders' misery compounded by the sending off of Zlatan Ibrahimovic in a 2-1 loss on Saturday.
Sakho turned the ball into his own net 10 minutes into the second half and, to make matters worse for PSG, Ibrahimovic was given a straight red card a quarter of an hour later for a challenge on goalkeeper Stephane Ruffier.
St. Etienne took advantage and two minutes later doubled its lead through Aubameyang, and although Guillaume Hoarau pulled one back with four minutes remaining, the hosts could not prevent their first loss of the season.
It had started well for PSG. Gregory van der Wiel's effort was turned away for a corner by Ruffier, with the visiting keeper then repelling Ibrahimovic's left-footed shot with his foot.
The second half followed the same pattern of PSG on the attack, with Javier Pastore heading Maxwell's free kick inches wide of the top corner with Ruffier rooted to the spot.
Despite PSG having had almost all the attacking play, it was St. Etienne that took a shock lead.
Aubameyang powered the ball across the edge of the six-yard box and home defender Sakho turned the ball into his own net.
Hoarau headed inches wide as PSG looked to respond but its task was made even harder when Ibrahimovic was given his marching orders.
The Sweden striker went in late on Ruffier following a through ball and the referee immediately gave him a straight red card.
St. Etienne doubled its lead two minutes later when Alejandro Alonso got down the right before picking out Aubameyang in the area, the forward beating Sirigu with a confident finish.
Hoarau pulled one back when he smashed home a half-volley across Ruffier but it was too little too late.
Valenciennes continued its free-scoring ways to move up to fourth in Ligue 1 with a convincing 3-1 victory over Sochaux.
Foued Kadir's 11th-minute strike was followed by a brace from Daniel Pujol that took Valenciennes to 23 goals for the season, and took it to within four points of the summit.
Sebastien Roudet registered for Sochaux but only after it had gone 3-0 down.
Lille sits seventh after stretching its unbeaten Ligue 1 run to four matches with a 2-0 victory at struggling Evian.
A goal late in the first half from Mevlut Erding saw Rennes claim their fourth win of the season and leapfrog 10-man Reims to move up to eighth.
However, the visitors deserve some credit for conceding a solitary goal given they had to play for 76 minutes with 10 men following the sending off of Pape N'Diaye Soure for a nasty challenge on Jonathan Pitroipa.
Eric Bautheac scored an 81st-minute winner as Nice pulled away from Ligue 1's bottom three with only its second win of the season, beating Nancy 2-1.
It appeared for a long time as though Nice was destined for its seventh draw in 11 league games this season, but Bautheac had other ideas, turning home a cut-back from Jeremy Pied.
An evenly-matched clash between Troyes and Montpellier ended with a fitting 1-1 draw at Stade de l'Aube.
Information from Press Association was used in this report.