Djibril Camara's last-gasp try gave Stade Français a shock win over last year's runners-up Castres to open the season.
Elsewhere Oyonnax came within minutes of a famous victory before eventually losing by a single point away at Toulouse.
And the two promoted sides La Rochelle and Lyon were given an idea of how far they still have to go, coming away with nothing from games at Brive and Bordeaux, with Brive going top thanks to a bonus-point success.
Earlier in the day Clermont were pushed all the way but held on to beat Grenoble on home soil.
Union Bordeaux-Bègles v Lyon OU
Stade André Moga, Bègles
Top 14 newcomers Lyon gave a good account of themselves but eventually came away with nothing in a tryless encounter with Bordeaux.
Lyon had made the better start, taking an early 6-0 lead thanks to two penalties from new man Stephen Brett, who arrived from Bayonne over the off-season.
However Bordeaux got back level before half-time with two penalties of their own through Pierre Bernard.
There was more of the same early in the second half with two more penalties from Bernard to stretch the Bordeaux lead to six points.
New signing Lionel Beauxis took over the kicking duties from Bernard, and added another three points with ten minutes to go, extending the lead to nine.
And while Lachie Munro gave Lyon some hope with a penalty eight minutes from time, Beauxis' second penalty sealed the win.
Pens: Bernard 4, Beauxis 2
Pens: Brett 2, Munro 1
Bordeaux: 15 Darly Domvo, 14 Sofiane Guitoune, 13 Julien Rey, 12 Thibaut Lacroix, 11 Blair Connor, 10 Pierre Bernard, 9 Heini Adams, 8 Matthew Clarkin (c), 7 Hugh Chalmers, 6 Louis-Benoit Madaule, 5 Adam Jaulhac, 4 Julien Le Devedec, 3 Patrick Toetu, 2 Clement Maynadier, 1 Jefferson Poirot.
Replacements:16 Benat Auzqui, 17 Jean-Baptiste Poux, 18 Jandre Marais, 19 Taisina Tuifua, 20 Baptiste Serin, 21 Lionel Beauxis, 22 Romain Lonca, 23 Francisco Gomez Kodela.
Lyon: 15 Romain Loursac, 14 Toby Arnold, 13 Kendrick Lynn, 12 Fabrice Estebanez, 11 Mosese Ratuvou, 10 Stephen Brett, 9 Ricky Januarie, 8 George Smith, 7 Pierrick Gunther, 6 Julien Puricelli, 5 Lionel Nallet (c), 4 Bjorn Basson, 3 Anthony Roux, 2 Vincent Colliat, 1 Wian Du Preez.
Replacements:16 Deon Fourie, 17 Bogdan Balan, 18 Joseph Tuineau, 19 Frans Viljoen, 20 Waisele Sukanaveita, 21 Paul Bonnefond, 22 Lachie Munro, 23 Horatiu Pungea.
Referee: Pascal Gauzère
Brive v La Rochelle
Stade Amédée-Domenech, Brive-la-Gaillarde
Brive moved top of the table with a bonus-point success as they came to life in the second half of their clash with La Rochelle.
The promoted side had the better of the first half, and through the boot of Jean-Pascal Barraque and scrum-half Julien Audy they led 9-6 on the stroke of half-time.
However with the final move of the half, Brive finally broke the shackles, taking advantage of an interception to send Gaetan Germain over.
They had a two-man advantage at the time, with Peter Grant and Levani Botia both in the sin-bin.
The Germain try seemed to be the spark the home side needed, and they took control at the start of the second half with a second try from an up and under, Alfie Mafi on hand to touch down.
Grant returned to bring La Rochelle back to 14 men, but with a man advantage Brive scored their third try, Thomas Laranjeira this time the man to cross.
It was soon Brive's turn to be down a man, when skipper Arnaud Mela was given a ten-minute break, but the home side continued to dominate, adding another penalty through Germain.
La Rochelle began to fight back, with Audy and then Grant adding penalties to reduce the deficit to 15.
But another score from winger Sevanaia Galala ensured that Brive would pick a bonus-point victory.
Tries: Germain, Mafi, Laranjeira, Galalala
Cons: Germain 3
Pens: Germain 3
Yellow cards: Mela
For La Rochelle:
Pens: Barraque 2, Audy 2, Grant
Yellow cards: Grant, Botia
Brive: 15 Gaetan Germain, 14 Alfie Mafi, 13 Arnaud Mignardi, 12 Thomas Sanchou, 11 Elia Radikedike, 10 Thomas Laranjeira, 9 Jean-Baptiste Pejoine, 8 Petrus Hauman, 7 Dominiko Waqaniburotu, 6 Hugues Briatte, 5 Arnaud Mela (c), 4 Peet Marais, 3 Kevin Buys, 2 Guillaume Ribes, 1 Goderzi Shvelidze.
Replacements:16 Thomas Acquier, 17 Karlen Asieshvili, 18 Victor Lebas, 19 Said Hireche, 20 Benjamin Neveu, 21 Andrew Malilei, 22 Sevanaia Galala, 23 Damien Jourdain.
La Rochelle: 15 Peter Grant, 14 Sireli Bobo, 13 Jean-Pascal Barraque, 12 Levani Botia, 11 Damien Cler, 10 Hamish Gard, 9 Julien Audy, 8 Jone Qovu, 7 Kevin Gourdon, 6 Romain Sazy, 5 Leandro Cesaro, 4 Jason Eaton, 3 Uini Atonio (c), 2 Rassie Van Vuuren, 1 Vincent Pelo.
Replacements:16 Hika Forbes, 17 Jordan Seneca, 18 Jacobus Grobler, 19 Nicolas Djebaili, 20 Albert Vulivuli, 21 Julien Berger, 22 Charles Lagarde, 23 Lekso Kaulashvili.
Referee: Christophe Berdos
Castres v Stade Français
Stade de la Méditerranée, Béziers
Djibril Camara's late try was enough for Stade Français to beat Castres, a first home Top 14 defeat for last year's runners-up in more than a season.
In a game played in Béziers, Stade Français had the better of the early stages, taking an early 11-3 lead thanks to a try from veteran winger Julien Arias.
However the visitors' indiscipline was proving costly, with Geoffrey Palis deadly from the kicking tee to put Castres back in front 12-11 at the break.
He added another early in the second half, but Stade moved back in front with their second try of the afternoon through their young flanker Mathieu Ugena.
But with nine minutes remaining Castres got the try they were desperate for, with winger Romain Martial crossing.
That looked like being the winner, but Stade reacted once more, with Camara grabbing the decisive score to give the Parisians a perfect start to the season.
Pens: Palis 5
For Stade Français:
Tries: Arias, Ugena, Camara
Cons: Plisson 2
Pens: Plisson 2
Castres: 15 Geoffrey Palis, 14 Romain Martial, 13 Thomas Combezou, 12 Romain Cabannes (c), 11 Remy Grosso, 10 Daniel Kirkpatrick, 9 Cedric Garcia, 8 William Whetton, 7 Mathieu Babillot, 6 Jannie Bornman, 5 Rodrigo Capo Ortega, 4 Christophe Samson, 3 Paea Fanuunu, 2 Mathieu Bonello, 1 Saimone Taumoepeau.
Replacements:16 Brice Mach, 17 Mihaita Lazar, 18 Piula Faaselele, 19 Johnnie Beattie, 20 Rory Kockott, 21 Remi Lamerat, 22 Julien Dumora, 23 Yohan Montes.
Stade Français: 15 Djibril Camara, 14 Julien Arias, 13 Waisea Nayacalevu, 12 Meyer Bosman, 11 Digby Ioane, 10 Jules Plisson, 9 Julien Tomas, 8 Sergio Parisse (c), 7 Sylvain Nicolas, 6 Mathieu Ugena, 5 Pascal Pape, 4 Paul Gabrillagues, 3 Rabah Slimani, 2 Laurent Sempere, 1 Heinke van der Merwe.
Replacements:16 Remi Bonfils, 17 Zak Taulafo, 18 Gerhard Mostert, 19 Scott Lavalla, 20 Jerome Fillol, 21 Raphael Lakafia, 22 Jonathan Danty, 23 Adrien Oleon.
Referee: Alexandre Ruiz
Stade Toulousain v Oyonnax
Stade Ernest Wallon, Toulouse
Toulouse were given an almighty scare as they inched past Oyonnax 20-19 in a display that was far from convincing.
On debut Toby Flood gave Toulouse the perfect start with a try after just ten minutes, finishing off the move after good work from Joe Tekori.
When he added a penalty to make it 8-0, Toulouse looked to be comfortable with Oyonnax down to 14 after a yellow card for Thibaut Lassalle.
However Oyonnax came back and nearly scored, only an intentional knock-on from Yannick Nyanga preventing a try, and leading to the French international being given ten minutes in the bin.
The visitors took full advantage, adding a penalty and a try through debutant
Soane Tonga'uiha to lead 10-8.
Flood and Benjamin Urdapilleta exchanged penalties at the end of the first half as the visitors led by two, but Flood added his second penalty of the afternoon soon after the break to put Toulouse back in front.
An infringement from Tekori allowed Oyonnax to take the lead once more, and Flood was off-target with seven minutes to go after former Toulouse man Yves Donguy had been penalised.
But with four minutes remaining he found his range, just edging over a penalty after Antoine Tichit was caught offside.
And Oyonnax were left fuming at the final whistle when Nyanga turned over the ball with time up when the referee appeared to have told him to take his hands off the ball.
Pens: Flood 5
Yellow cards: Nyanga
Pens: Urdapilleta 4
Yellow cards: Lasalle
Toulouse: 15 Alexis Palisson, 14 Vincent Clerc, 13 Yann David, 12 Clement Poitrenaud, 11 Timoci Matanavou, 10 Toby Flood, 9 Jano Vermaak, 8 Joe Tekori, 7 Imanol Harinordoquy, 6 Yacouba Camara, 5 Patricio Albacete (c), 4 Romain Millo-Chluski, 3 Neemia Tialata, 2 Cyril Baille, 1 Vasil Kakovin.
Replacements:16 Christopher Tolofua, 17 Rodrigue Neti, 18 Gregory Lamboley, 19 Yannick Nyanga, 20 Jean Marc Doussain, 21 Gael Fickou, 22 Yoann Huget, 23 Census Johnston.
Oyonnax: 15 Florian Denos (c), 14 Dug Cudjo, 13 Guillaume Bousses, 12 Roimata Hansell-Pune, 11 Yves Donguy, 10 Benjamin Urdapilleta, 9 Agustin Figuerola, 8 Viliame Ma'afu, 7 Mauri Fa'asavalu, 6 Pedrie Wannenburg, 5 Damien Lagrange, 4 Thibaut Lassalle, 3 Ruaan Du Preez, 2 Jody Jenneker, 1 Soane Tonga'uiha.
Replacements:16 Clement Julien, 17 Marc Clerc, 18 Damian Browne, 19 Olivier Missoup, 20 Fabien Cibray, 21 Riaan Smit, 22 Alex Luatua, 23 Antoine Tichit.
Referee: Maxime Chalon