Grenoble caused a major shock in the Top 14 on Friday by stunning French heavyweights Stade Français 26-12.
In what was their second win of the season, the top flight new-boys scored two tries to zero at Stade Lesdiguières to upset the Parisians.
Their five-pointers came via Rida Jaouher and Lucas Dupont while Valentin Courrent added sixteen valuable points from the kicking tee.
For Stade Français this is their second defeat from their three openers as only Jerome Porical could trouble the scorers with four penalties.
Grenoble's advantage was a slender three points at the break as Courrent and Porical traded shots to send the teams in at 9-6 in favour of the hosts.
Porical levelled matters soon after the turnaround before centre Jaouher crossed for a converted try that lifted the weather-battered home supporters.
The two kickers were at it again on 51 and 57 minutes but for Porical it was to be his last contribution as Grenoble finished with a flourish, Dupont scoring his try to seal victory.
Tries: Jahouer, Dupont
Con: Courrent 2
Pen: Courrent 4
For Stade Français:
Pen: Porical 4
Grenoble: 15 Fabien Gengenbacher, 14 Lucas Dupont, 13 Rida Jaouher, 12 Nigel Hunt, 11 Joaquin Tuculet, 10 Blair Stewart, 9 Valentin Courrent, 8 Shaun Sowerby, 7 Roland Bernard, 6 Jonathan Best, 5 Naude Beukes, 4 Benjamin Hand, 3 Dayna Edwards, 2 Vincent Campo Castillo, 1 Gregory Fabro.
Replacements: 16 Kenan Mutapcic, 17 Laurent Bouchet, 18 Cyril Veyret, 19 Henry Vanderglas, 20 Viliame Waqaseduadua, 21 Aloisio Butonidualevu, 22 Jonathan Pelissie, 23 Karim Kouider.
Stade Français: 15 Jerome Porical, 14 Waisea Vuidravuwalu, 13 Morgan Turinui, 12 Paul Williams, 11 Paul Sackey, 10 Felipe Contepomi, 9 Jerome Fillol, 8 Sergio Parisse, 7 Olivier Missoup, 6 Scott Lavalla, 5 Pascal Pape, 4 Anton van Zyl, 3 David Attoub, 2 Laurent Sempere, 1 Romain Frou.
Replacements: 16 Remi Bonfils, 17 Rabah Slimani, 18 Alexandre Flanquart, 19 David Lyons, 20 Julien Dupuy, 21 Paul Warwick, 22 Hugo Bonneval, 23 Zurabi Zhvania.
Referee: Jean-Luc Rebollal