Perpignan and Toulon gained automatic semi-final qualification on Saturday while Toulouse and Clermont secured home play-offs.
Montauban earned their place in the Top 14 on the field with victory over Bayonne, so it is now up to their administrators to sort out their finances to avoid relegation.
For the second consecutive year, Perpignan finish the season at the top of the standings thanks to their 44-point drubbing of Albi. The defending champions beat Toulon to the top spot on points difference.
Biarritz managed to save a losing bonus point at home to Clermont, meaning the Basques grab seventh spot.
Stade FranÃ§ais finished their dismal season on a high note with victory over Racing Metro in the Paris derby while Montpellier put on a show for their fans to beat Bourgoin and finish tenth.
The play-offs will see Clermont host Racing Metro, while Toulouse will have a rematch with Castres.
Toulouse 25-17 Castres
Montauban 22-8 Bayonne
Biarritz 19-26 Clermont
Stade FranÃ§ais 41-17 Racing Metro
Brive 23-26 Toulon
Perpignan 44-0 Albi
Montpellier 34-27 Bourgoin
1 Perpignan 80
2 Toulon 80
3 Clermont 78
4 Toulouse 74
5 Castres 73
6 Racing MÃ©tro 64
7 Biarritz 59
8 Stade FranÃ§ais 58
9 Brive 57
10 Montpellier 55
11 Bourgoin 50
12 Montauban 49
13 Bayonne 47
14 Albi 24
Clermont v Racing
Toulouse v Castres
Perpignan have chosen to host their semi-final at Stade de la Mosson in Montpellier (against Toulouse or Castres) meaning Toulon will play at Stade Geoffroy-Guichard in St. Etienne (against Clermont or Racing).
Stade Toulousain 25-17 Castres Olympique
Stade Ernest Wallon, Toulouse
The giants from the south-west had to dig deep against their neighbours, but the former champions came up with the goods when needed and can look forward to two knock-out games in as many weeks in the Vill Rose.
Jean-Baptiste Elissalde gave Toulouse an early lead with a drop and a penalty but Castres were ahead 12-6 at the break as Romain Teulet punished the undisciplined hosts from the kicking tee.
Toulouse came out the change rooms a different side however and the attacking inaccuracies of the first half were soon forgotten as wings Vilimoni Delasau and Cedric Heymans each scored within ten minutes of the restart to put les Toulousains back in front.
There was more drama to follow when Castres centre Laurent Cabannes won a footrace to flank Yannick Caballero's kick ahead to reduce the deficit to a single point.
With Toulouse pushing for another try and Castres trying to defend their losing bonus point, visiting prop Mathieu Bonello was yellow carded with four minutes left , paying the price for his side's increasingly cynical play
A huge scrum from the Toulouse pack set up number eight Finau Maka, who crashed over. Skrela's conversion denied Castres a bonus point and handed Toulouse a home play-off.
Montauban 22-8 Aviron Bayonnais
Stade Sapiac, Montauban
And now the wait begins. In strictly sporting terms, Montauban deserve a place in the Top 14 but can they find the â‚¬1.7m in the next 24 hours to win their appeal against administrative relegation and avoid liquidation?
Their club president suggested that he had found two investors ready to come up with the money on condition that they won on Saturday...
The home side dominated Bayonne in every department and the Basques will look back in regret at their negative tactics.
Montauban deserved their 14-3 half-time lead. Winger Jean-Emmanuel Cassin's try was just reward for some enterprising play and Julien Audy's boot ensured they stayed ahead.
In the second half, home centre Jean-philippe Viard slotted a drop but Bayonne wing Sam Gerber kept his team in the hunt with a try in the 57th minute.
Montauban's replacement fly-half Johan Dalla Riva scored in the 80th minute on the counter attack to secure victory for the hosts.
CA Brive-CorrÃ¨ze 23-26 RC Toulon
Stade AmÃ©dÃ©e Domenech, Brive
It's settled: Brive will not be in the Heineken Cup next year. A ding-dong battle in the CorrÃ¨ze finally went the way of the visitors thanks to the strength of their bench.
Toulon scrum-half Fabien Cibray replied to Alexis Pallison's opening penalty with a drop goal, but Brive full-back Scott Speeding put the hosts ahead with a try on 14 minutes.
Pallison added the conversion before Contepomi Felipe - who was at fly-half for Toulon in the absence of Jonny Wilkinson - landed two penalties.
But Fabrice Estebanez cancelled out Contepomi's efforts to give Brive a 16-9 lead at half-time.
The face of the game changed when Pierre Mignoni and Joe van Niekerk came off the bench.
Mignoni created a try for Fijian wing Gabiriele Lovobalavu to level the scores with half-an-hour to play. Mignoni was again at the origin as Sonny Bill Williams crashed over. Contepomi added a penalty to give Toulon a ten-point lead.
But five minutes from time Argentine wing Horacio Agulla set up a grandstand finish when he scored in the corner and Luciano Orquera hit the target with his conversion.
Toulon however hung to in the dying minutes to finish joint-top of the standings and book a place in the semi-finals.
Biarritz Olympique 19-26 Clermont Auvergne
Parc des Sports d'Aguilera, Biarritz
A losing bonus point for Biarritz gives the Basques an extra hope of making the Heineken Cup - even if the don't win it, if Toulouse do, seventh place will be enough to sneak in through the back door.
It could have ended the other way for Biarritz, but some slopping finishing and three TMO decisions against them meant they missed out on victory.
Clermont's home play-off came at the price of Mario Ledesma and Morgan Parra, who sustained knee and rib injuries respectively.
Damien Traille put the hosts in front after just three minutes with his now-standard drop goal, but Clermont wrestled the lead back as Parra and Brock James each landed a penalty.
Dimitri Yachvili leveled the scores from the kicking tee but Clermont's Fijian try-machine Napolioni Nalaga moved them back in front with the first of his two tries.
James extended the lead but Yachvili put the hosts right back in the picture with a penalty directly after the restart and try a few minutes later.
Nalaga crossed again with less than twenty minutes on the clock before Parra cancelled out Yachvili's final penalty.