French leader Marseille 's perfect start to the season came to an emphatic end on Sunday, when it lost 4-1 to Valenciennes with goalkeeper Steve Mandanda gifting one of the goals by making a huge blunder.
Gael Danic and Anthony Le Tallec put Valenciennes 2-0 up after 35 minutes, and Mandada then rolled the ball out straight to Foued Kadir for the Algeria midfielder to make it 3-0 to the hosts.
Le Tallec scored his second of the game midway through the second half, before Marseille substitute Jordan Ayew pulled a goal back in injury time.
Marseille won its opening six matches.
''It's a heavy defeat, when we went in at halftime 3-0 down the game was over for us,'' Marseille coach Elie Baup said. ''After their first goal we had some chances, we could have got back to 1-1, but we couldn't do it. When you lose like that, it means that very little went right.''
Lyon can trim Marseille's lead at the top and reclaim second place from Paris Saint-Germain by beating Bordeaux at home later Sunday. Also, Saint-Etienne hosts Reims.
Marseille lined up with a three-man wall after giving away a freekick in the 15th minute, and Danic curled the ball superbly into the top right corner.
Poor defending led to the second goal, as right back Rod Fanni hesitated as he tried to clear the ball and Danic took it off him before finding Le Tallec with a pass.
After scoring the third goal in the 39th, Kadir set up the fourth, breaking down the left and crossing the ball for Le Tallec, who beat Mandanda with a downward header.
With France's World Cup qualifier away to world and European champion Spain a little over two weeks away, Mandanda's performance will be of concern to coach Didier Deschamps, with his first-choice goalkeeper Hugo Lloris stuck on the bench at Tottenham and lacking match practice.
Marseille has a big week coming up with a home game against AEL Limassol in the Europa League on Thursday, followed by a home match against bitter rival PSG on Sunday.
''We have to put this game to one side and look ahead,'' Baup said. ''We will have to pull ourselves together, analyze what went wrong in the cold light of day and get back to how we were playing before.''