Paris St Germain face a stern test of their surprise title challenge when they travel to second-placed Girondins Bordeaux on Sunday (2000 GMT) as Ligue 1 matches resume after the winter break.
PSG, who escaped relegation in the final round of matches last season, are fourth in the standings with 33 points from 19 games, two points adrift of Bordeaux.
Seven-times champions Olympique Lyon lead the pack on 38 points and host FC Lorient on Saturday (2000).
"It will be a tough game," Stephane Sessegnon, the driving force of the team's midfield, told his club's website.
"It might not be the turning point of the season but it's definitely one of our most important games."
The capital side, who won the Cup Winners' Cup in 1996, have not been crowned champions since 1994 while Bordeaux, who last prevailed in 1999, finished second last season.
Both teams are expected to be at full strength for Sunday.
Olympique Lyon, the ruling power of French football, kick off 2009 with a slim margin over their rivals.
Last season, Lyon resumed their campaign after the winter break with a six-point lead over then third-placed Bordeaux and had built 15 and 12 point gaps to nearest challengers Lens in 2006/07 and 2005/06.
Claude Puel's side will be the only side to have not yet played a game this year after last weekend's French Cup match at amateurs Concarneau was twice postponed because of a frozen pitch.
However midtable Lorient, who have taken 20 points from their last 10 league matches and shown strong form away from home, are without several key players.
Influential midfielder Ulrich Le Pen has flu and striker Kevin Gameiro is also ill, according to the Brittany club, while forward Rafik Saifi is doubtful with an ankle injury.
Surprise third-placed Stade Rennes, who are interested in signing Chelsea's Danish forward Morten Nielsen, are four points off the pace and host promoted Grenoble on Saturday (2000).
"The idea is not to weaken the squad before the end of the transfer window," Rennes manager Pierre Dreossi told French sport daily L'Equipe's website on Wednesday.
Fifth-placed Olympique Marseille, who suffered a 3-0 home defeat to Nancy before the holidays, will be looking to recover some ground when they travel to AJ Auxerre on Saturday (2000).
The Provence side could be without creative midfielder Mathieu Valbuena, who sustained a groin injury in Sunday's penalty shootout French Cup win at Besancon.
