Racing 92 can continue their march towards a historic season at home to struggling Castres in the French Top 14 on Saturday.

The Parisians top the table after 14 matches and just two league defeats this season -- four fewer than European champions Toulon, who are second.

They were also amongst the top seeds to qualify for the European Champions Cup quarter-finals and will host the holders in April.

And while many other sides will have their star players engaged in Six Nations action this weekend, Racing can count on New Zealand legend Dan Carter to lead their charge against the 2013 champions at the Stade Yves du Manoir.

Racing won't be without absentees as the likes of scrum-half Maxime Machenaud, hooker Camille Chat and back-rower Wenceslas Laurent remain with the French squad.

Castres will be weakened by the absence of Scotland lock Jonny Gray but Samoan-born wing David Smith is available after the debacle of his France call-up.

Last weekend, the 29-year-old was selected for the French squad having supposedly qualified over residency rules.

But on arriving at the French Marcoussis training base near Paris, Smith told officials he had played in an international Sevens tournament for New Zealand in 2008, meaning he is not eligible to play for France.

Racing have a two-point lead at the top but Toulon, who host Brive on Saturday, have played a game more and the nearest challengers to have played 14 matches, Toulouse and Clermont, are five points back.

Racing picked up only their second bonus point of the season in a thrilling 39-35 win at Grenoble -- compared to the 10 Toulon have earned so far -- in which they showed signs of greater expansiveness in their play.

The Parisians are trying not to get carried away, but expectation is growing amongst fans waiting for owner Jacky Lorenzetti's heavy investment to start bearing fruit.

Last weekend, Clermont also showed signs of improvement as they scored two tries in the final seven minutes to win 28-17 at Castres.

That came on the back of three successive home defeats in the league for a team that used to be known as unbeatable in their Marcel Michelin colosseum.

They will host Oyonnax on Saturday in a game that could serve to precipitate the visitors' return to the second division.

Oyonnax, in a third successive top flight season, are 10 points from safety following their 43-13 home thrashing by Toulon last weekend, coupled with Pau's shock 19-16 win at Montpellier.

Alongside rock bottom Agen, who host La Rochelle, Oyonnax appear to already be doomed to relegation.

Manager Johann Authier admitted as much following the Toulon defeat, saying: "We have one foot in the Pro D2 (2nd division)."

That was word for word a repeat of Agen manager Mathieu Blin's own statement following a home defeat to Grenoble in late January.

With Pau at home to Bordeaux-Begles and champions Stade Francais hosting Grenoble -- both very winnable games for the sides in the last two safety positions -- defeat for Oyonnax or Agen could see the gap to safety grow even more by the end of the weekend.

Fixtures (1730 GMT unless stated)

Saturday

Toulon v Brive (1330), Stade Francais v Grenoble, Agen v La Rochelle, Clermont v Oyonnax, Pau v Bordeaux-Begles, Racing 92 v Castres (1945)

Sunday

Toulouse v Montpellier (1515)
Source :AFP