Defending champions Marseille moved into second place in the French top flight after edging arch-rivals Paris Saint-Germain 2-1 at Stade Velodrome on Sunday.
All the goals came in the first half, with the excellent Andre Ayew giving Marseille victory after Clement Chantome had cancelled out Gabriel Heinze's free-kick opener for the hosts.
Victory avenged Marseille's 2-1 defeat in November's reverse fixture and takes Didier Deschamps's side to within four points of league leaders Lille with 10 matches remaining.
"It's a very good result for us, against a direct rival," said Marseille coach Deschamps.
"Lille remain the most well-armed, because of their league position and the quality of their play. But we're hanging in there.
"There was determination and desire tonight and we have to keep that spirit."
PSG remain fifth, six points behind OM and five points shy of the Champions League qualification places, and have now gone five games without a win in all competitions.
"We're doing very badly in terms of picking up points, but we've just played 11 matches in five weeks," said PSG coach Antoine Kombouare.
"There are 10 matches left. If we finish fifth it would be good, but I hope to see my team climb a few places."
Both sides were smarting after bowing out of European competition in the week, Marseille having lost to Manchester United in the Champions League before PSG were eliminated from the Europa League by Benfica.
The home side took the lead with the first chance of the game in the 16th minute, as PSG old boy Heinze -- who scored the only goal in last season's fixture -- bent a fine 22-yard free-kick into the bottom-left corner.
PSG goalkeeper Gregory Coupet, replacing the out-of-form Apoula Edel, was at fault for the goal after positioning himself behind the wall, but the visitors' equaliser owed just as much to disorganisation in the opposing defence.
Marseille spurned several opportunities to clear the ball, allowing Nene to fire a shot against the right-hand post, and midfielder Chantome followed up to slam the rebound home.
The hosts' lead had only lasted 11 minutes but they restored their advantage eight minutes later.
Andre-Pierre Gignac curled in a left-foot cross from the right flank that Ghana international Ayew converted with a firm header from six yards.
Former Lyon goalkeeper Coupet did not have a save to make until the 48th minute, but he got down well to repel Ayew after a marauding run.
Coupet's opposite number, France number two Steve Mandanda, proved equally alert at the other end when he denied Guillaume Hoarau from close range shortly before the hour.
Earlier in the day, Monaco squandered the chance to move out of the relegation zone by losing 1-0 at home to direct rivals Nancy.
Brazilian centre-back Andre Luiz claimed the game's only goal, rising to meet Julien Feret's corner with a crashing header in the 18th minute.
Monaco remain third from bottom, three points from safety, while Nancy climb three places to 14th, six points clear of danger.
"Perhaps a draw would have been fair on the balance of play, but this season at Stade Marcel-Picot I've seen Nancy play better and lose," said Nancy coach Pablo Correa.
In the day's other afternoon kick-off, late goals from Yohan Mollo and Youssef El Arabi saw Caen defeat bottom club Arles-Avignon 2-0 to move up to 13th.
Lille are now four points clear after coming from behind to win 2-1 at Brest on Saturday.
Rennes finished the weekend in third place, and Lyon fourth, after Kevin Theophile-Catherine's 87th-minute header earned Rennes a 1-1 draw in the meeting between the sides at Stade Gerland.