A goal from Ludovic Giuly earned Paris St Germain a 1-0 win over seven-times French champions Olympique Lyon on Saturday.
Lyon have dominated in France for seven years and victory would have sent them eight points clear at top of the standings.
But former Barcelona winger Giuly, who is 1.64m tall, headed home in the 26th minute to give PSG all three points in Paris and Marseille will have the opportunity to narrow the gap on Lyon to four points when they host Lille on Sunday (2000GMT).
Lyon prepared for Tuesday's Champions League trip to Fiorentina in the worst possible fashion.
They lost defender Anthony Reveillere, who left the pitch after 11 minutes with a suspected torn knee ligament following a clash with PSG midfielder Stephane Sessegnon.
Juninho, who replaced striker Karim Benzema in the 59th minute, was shown a straight red card 14 minutes from time after a nasty tackle on PSG defender Sylvain Armand.
PSG, who escaped relegation in the last round of matches last season, jumped three spots to fifth on 26 points, seven points adrift of Lyon.
Surprise package Nice moved to second on 28 points when an Olivier Echouafni first-half goal earned them a 1-0 win at St Etienne as the 10-times French champions hit the bottom of the standings.
Echouafni headed home from a David Hellebuyck corner kick to inflict St Etienne's seventh consecutive league defeat despite changing coach earlier this month.
"The players did not deserve this. We showed a lot of conviction but we were not lucky," Alain Perrin, who took over from Laurent Roussey earlier this month, told St Etienne's website (www.asse.fr).
"There were signs of hope, we must go on like this."
Stade Rennes extended their unbeaten run to 13 league matches when they snatched a 1-1 draw at sixth-placed Girondins Bordeaux.
Fourth-placed Rennes opened the scoring through midfielder Olivier Thomert in the 19th minute, only for France playmaker Yoann Gourcuff to level just before the hour.
Toulouse missed a chance to move into the top three when they lost 1-0 at Lorient and dropped to seventh.