The 101st Basque Derby on Saturday promises to be the most dramatic in years as it is likely to decide the fate of hosts Bayonne.
Although separated by just 5km, Stade Jean-Dauger in Bayonne and Parc des Sports AguilÃ©ra in Biarritz are world's apart. Few rivalries in world sport can compare and with so much on the line, few would be surprised if this weekend's battle saw a repeat of the mass punch-up that made headlines when these team last met.
The Basque rivals aren't the only ones fighting for survival though and Perpignan are under pressure to produce the goods against leaders Toulouse.
With four rounds left to play, Parisian rivals Racing-Metro and Stade FranÃ§ais remain locked in their battle for the sixth place that will ensure play-off rugby at the end of the regulation season. Racing host Brive while Stade travel to buoyant Clermont, who now harbour realistic dreams of the French-European double in their centenary season.
Elsewhere, Castres and Montpellier are chasing home play-offs when they host Lyon and Bordeaux-BÃ¨gles respectively.
Friday, April 13
Perpignan v Toulouse
Saturday, April 14
Agen v Toulonnais
Clermont v Stade FranÃ§ais
Montpellier v Lyon
Racing MÃ©tro v Brive
Bayonne v Biarritz
Castres v Bordeaux-BÃ¨gles
Rugby Union betting odds
1 Toulouse 78
2 Clermont 74
3 Toulon 63
4 Montpellier 57
5 Castres 55
6 Racing MÃ©tro 54
7 Stade FranÃ§ais 53
8 Agen 44
9 Brive 42
10 Biarritz 42
11 Bordeaux-BÃ¨gles 41
12 Perpignan 40
13 Bayonne 34
14 Lyon 30
USA Perpignan v Stade Toulousain
Stade AimÃ© Giral, Perpignan
Two clubs in very different situations face off on the Mediterranean coast to kick the weekend off.
Just six points clear of the relegation zone, Perpignan cannot afford defeat.
Toulouse meanwhile have already booked a place in the semi-finals will be tempted to put the machine into cruise control and keep their powder dry.
Guy NovÃ¨s has nevertheless picked a very strong team, mixing the need to rest some of his internationals by leaving them on the bench with the need to line up a winning team. Luke Burgess starts as he continues his return from injury while Yannick Jauzion is back in midfield with Clement Poitrenaud at full-back. Pumas lock Patricio Albacete is also back in the starting XV.
Jean-Marc Doussain starts at fly-half while AurÃ©lien ImpÃ©rial makes his second appearance at professional level.
Perpignan - who have not lost at home since late November - have been able to select close to their strongest side with French international duo David Marty and Maxime Mermoz in midfield, Jame Hook at 10 and Nicolas Mas leading the pack.
Perpignan: Michel, Sid, Marty, Mermoz, Plante, Hook, Cazenave, Guiry, Chouly, Le Corvec, Taofifenua, Olibeau, Mas, Geli, Freshwater
Replacements: Guirado, Schuster, Britz, Tachale Watchou, Mele, Porical, Hume, Bourrust.
Toulouse: Poitrenaud, ImpÃ©rial, David, Jauzion, Donguy, Doussain, Burgess, Nicolas, Galan, Nyanga, Albacete, Lamboley, MontÃ¨s, Tolofua, Poux.
Replacements: Servat, Human, Maestri, Sowerby, Vergallo, Beauxis, Dusautoir, Johnston
Previous result Toulouse won 21-17 at home
Prediction: Toulouse have won just three times in 19 games in Perpignan in the post-war era. The hosts have much more to play for. Perpignan by six points
Kick-off: 20.45 (18.45 GMT)
Referee: Christophe Berdos
SU Agen v RC Toulon
Stade Armandie, Agen
After an exceptional start to their campaign, Agen have faded in the second half of the season, winning just three times in 11 games.
Saturday's hosts are coming off the back of a three-game losing streak but need just two points to ensure their place in the top flight.
But Toulon are within reach of securing a home play-off and the visitors and will travel with serious ambitions of securing their first win in Agen in 15 attempts.
Jonny Wilkinson picked up knock against Harlequins and will not travel west but les Toulonnais welcome back Argentine loose forward Juan-Martin Fernandez-Lobbe.
The Agen pack has been decimated by injury with four first-choice players (Nnomo, Fono, Fonua, Fa'aoso) all not available.
Previous result: Toulon won 34-12 at home
Prediction: Amlin Challenge Cup semi-finalists Toulon should be too strong. Toulon by eight points
Kick-off: 14.15 (12.15 GMT)
Referee: Neil Paterson (Scotland)
ASM Clermont Auvergne v Stade FranÃ§ais Paris
Parc des Sports Marcel Michelin, Clermont Ferrand
Stade FranÃ§ais produced one of the best performances of their season at home to Clermont back in November but they'll have to be even better to become the first team to win in the Auvergne in over two years.
Indeed, Clermont have lost just one game in all competitions since mid-December (in Biarritz) and the Heineken Cup semi-finals will be eyeing the championship lead.
Les Jaunards' victory over Saracens last week came at cost though as David Skrela has been ruled out while Jamie Cudmore and Wesley Fofana are doubtful starters. Morgan Parra is being rested.
For all their positive results in Paris, Stade FranÃ§ais have been terrible on the road - winning just once in ten games - so are unlikely to cause an upset at fortress Marcel Michelin.
Former Clermont hooker Mario Ledesma returns to Volcano Country in a pink tracksuit as Stade FranÃ§ais forwards coach. Fly-half Felipe Contepomi is doubtful after picking up a knock against Exeter. Internationals Pascal PapÃ©, Dimitri Szarzewski and Sergio Parisse are being rested.
Previous result: Stade FranÃ§ais 37-16 at home
Prediction: Only a mad man would bet against Clermont at home. Clermont by twelve points
Kick-off: 14.15 (12.15 GMT)
Referee: Laurent Cardona
Montpellier HR v Lyon Olympique
Stade Yves Du Manoir, Montpellier
Montpellier are neck-and-neck with Castres in the race for a home play off. With tough fixtures against Clermont and Toulouse on the menu at the end of the season, Montpol will be aiming for a bonus point on home soil.
The home side were given a boost in morale on Tuesday when forwards coach Eric BÃ©chu returned from sick leave, 40kg lighter (!) but smiling and motivated to help his team push for a place in the finals.
Lyon are still alive mathematically but few would bet on them avoiding the drop. That said, victory against Bordeaux last time out has reignited their hopes, so they won't be pushovers.
Previous result: Montpellier won 30-10 in Lyon
Prediction: The home side should be