Clermont ran nine unanswered tries past Bordeaux-BÃ¨gles on Saturday to finish the Top 14 regular season at the summit of the standings.
A losing bonus point away to Racing MÃ©tro was enough for Castres to claim a home play-off. They will host Montpellier, who smashed Perpignan to climb into fifth place.
European Cup finalists Clermont established a new French record of 60 successive home wins in all competitions.
Clermont beat the mark they shared with Stade FranÃ§ais of 59 which the Parisian club established between September 2004 and March 2008.
Clermont's last home loss dates back to November 21, 2009 (against Biarritz.)
Having finished top of the standings they, like runners-up Toulon, get a week off while third to sixth placed teams play for the honour of reaching the semi-finals.
Toulouse v Racing MÃ©tro
Castres v Montpellier
Semi-finals: (Both to be played in Nantes)
May 24: Toulon v Toulouse or Racing Metro
May 25: Clermont v Castres or Montpellier
1 Clermont 91
2 Toulon 90
3 Toulouse 79
4 Castres 74
5 Montpellier 73
6 Racing Metro 73
7 Perpignan 61
8 Bayonne 57
9 Biarritz 57
10 Stade FranÃ§ais 54
11 Grenoble 54
12 Bordeaux Begles 47
13 Agen 31
14 Mont-de-Marsan 16
Racing MÃ©tro 29-28 Castres
Montpellier 50-22 Perpignan
Toulouse 57-7 Grenoble
Clermont 67-3 Bordeaux-BÃ¨gles
Toulon 43-21 Agen
Biarritz 52-17 Stade FranÃ§ais
Mont-de-Marsan 33-36 Bayonne
Racing MÃ©tro 29-28 Castres Olympique
Stade Yves Du Manoir - Colombes (Paris)
Racing-Metro could have avoided the unwelcome trip to Toulouse if they had beaten fourth-placed Castres with an offensive bonus point and denied their opponents a defensive one on Saturday.
Victory wasn't enough and Castres - whose coaches Laurent Labit and Laurent Travers will be at Racing next season - will host 2011 finalists Montpellier next Saturday.
Racing led 22-6 at half time but Castres came charging back with three unanswered tries to take the lead.
However a 77th minutes try by replacement prop Eddy Ben Arous gave Racing the win.
For Racing MÃ©tro:
Tries: Bobo, Ben Arous
Cons: Wisniewski, Machenaud
Pens: Wisniewski 5
Tries: Cabannes, Garvey, Kockott
Cons: Kockott 2
Pens: Kockott 2, Teulet
Yellow cards: Taumoepeau, Caballero
Racing MÃ©tro: 15 Juan Martin Hernandez, 14 Julien Jane, 13 Henry Chavancy, 12 Fabrice Estebanez, 11 Sereli Bobo, 10 Jonathan Wisniewski, 9 Maxime Machenaud, 8 Masinivanua Matadigo, 7 Bernard Le Roux, 6 Antoine Battut, 5 Francois Van der Merwe, 4 Fabrice Metz, 3 Luc Ducalcon, 2 Dimitri Szarzewski, 1 Julien Brugnaut.
Replacements: 16 Thomas Bianchin, 17 Eddy Ben Arous, 18 Manuel Carizza, 19 Alvaro Galindo, 20 Sebastien Descons, 21 Alexandre Dumoulin, 22 Virimi Vakatawa, 23 Salemane Sa.
Castres: 15 Brice Dulin, 14 Romain Martial, 13 Romain Cabannes, 12 Max Evans, 11 Marcel Garvey, 10 Remi Tales, 9 Rory Kockott, 8 Antonie Claassen, 7 Yannick Caballero, 6 Ibrahim Diarra, 5 Rodrigo Capo Ortega, 4 Christophe Samson, 3 Karena Wihongi, 2 Mathieu Bonello, 1 Saimone Taumoepeau.
Replacements: 16 Marc Antoine Rallier, 17 Michael Coetzee, 18 Matthias Rolland, 19 Jan de bruin Bornman, 20 Thierry Lacrampe, 21 Daniel Kirkpatrick, 22 Romain Teulet, 23 Anton Peikrishvili.
Montpellier HÃ©rault Rugby 50-22 USA Perpignan
Stade Yves Du Manoir, Montpellier
Montpellier outclassed 2009 champions Perpignan - who sent a below full-strength side - and will face Castres for a third successive year in the play-offs, both having won one apiece.
Montpellier led 22-0 at half time.
Tries: Penalty try, Tulou, Sicart, Bustos Moyano 2, Tupuola, Paillaugue
Cons: Bustos Moyano 6
Pen: Bustos Moyano
Tries: Piukala, Taofifenua, Guitoune, Catala
Yellow card: Pulu
Montpellier: 15 Benoit Sicart, 14 Taleta Tupuola, 13 Thomas Combezou, 12 Santiago Fernandez, 11 Martin Bustos Moyano, 10 Francois Trinh-Duc, 9 Julien Tomas, 8 Alex Tulou, 7 Kelian Galletier, 6 Fulgence Ouedraogo, 5 Mamuka Gorgodze, 4 Hendrikus Hancke, 3 Maximiliano Bustos, 2 Agustin Creevy, 1 Mikheil Nariashvili.
Replacements: 16 Charles Geli, 17 Nahuel Lobo, 18 Mickael De Marco, 19 John Beattie, 20 Benoit Paillaugue, 21 Hamish Gard, 22 Pierre Berard, 23 Vincent Pelo.
Perpignan: 15 Joffrey Michel, 14 Adrien Plante, 13 Sofiane Guitoune, 12 Sione Piukala, 11 Armand Batlle, 10 Gavin Hume, 9 David Mele, 8 Luke Narraway, 7 Bertrand Guiry, 6 Romain Bezian, 5 Bobins Tchale Watchou, 4 Guillaume Vilaceca, 3 Jeremy Castex, 2 Romain Terrain, 1 Sebastien Taofifenua.
Replacements: 16 Guilhem Guirado, 17 Kisi Pulu, 18 Romain Taofifenua, 19 Gilles Arnaudies, 20 Florian Cazenave, 21 David Marty, 22 Fabrice Catala, 23 Jerome Schuster.
Stade Toulousain 57-7 Grenoble
Stade Ernest Wallon, Toulouse
Toulouse led 22-0 at half time as they cruised to victory to claim third spot and secure a home play-off.
France number eight Louis Picamoles is a doubtful starter for Toulouse in next Friday's play-off with Racing-Metro after he was injured in their 57-7 trouncing of Grenoble.
Toulouse head coach Guy NovÃ¨s, who is bidding to guide Toulouse to their third successive title, said that Picamoles had suffered injuries to a shoulder, a thigh and a deep bruising to a calf muscle.
"He is doubtful for the match but we hope to have him back for the semi-final should we reach it," said the 59-year-old.
NovÃ¨s, who in his tenure at Toulouse has guided them to 10 French titles and a record four European Cups, said that aside from Picamoles, who went off at half-time, there were no other injury worries.
"The preparations for the play-off begin now," said Noves.
"It will be an interesting week just as we like them."
Tries: Fickou, Huget 2, Fritz, Nyanga, Bouilhou, Lamboley, Johnston
Cons: McAlister 2, Beauxis 5
Toulouse: 15 Clement Poitrenaud, 14 Yoann Huget, 13 Yannick Jauzion, 12 Gael Fickou, 11 Yann David, 10 Luke McAlister, 9 Luke Burgess, 8 Louis Picamoles, 7 Yannick Nyanga, 6 Jean Bouilhou, 5 Yoann Maestri, 4 Edwin Maka, 3 Vasil Kakovin, 2 William Servat, 1 Gurthro Steenkamp.
Replacements: 16 Jaba Bregvadze, 17 Jean Batiste Poux, 18 Romain Millo Chlusky, 19 Gregory Lamboley, 20 Jean Marc Doussain, 21 Lionel Beauxis, 22 Florian