RUAN Pienaar kicked all the nine penalty points as Ulster recorded a win for the first time in France.
It was an ugly performanc by Mark Anscombe’s men on French soil.
There were a lot of mistakes in the line out, a few handling errors but the scrum remained strong and resolute.
But a win is a win, particularly in France with travelling Ulster fans cheering them on from the stands.
Pienaar moved to the No 10 fly-half position and Craig Gilroy started at full-back for the Heineken Cup clash against Castres Olympique.
The win means that Ulster get a home tie in the quarter finals of the Heineken Cup.
Gilrory stepped in for Jared Payne, who was out injured because of groin strain, while Michael Allen will make his first European start on the left wing.
Mark Anscombe made six changes for the game at Stade Pierre-Antoine including moving Paddy Jackson to the bench as Ruan Pienaar starts at 10.
The South African partnered by Paul Marshall, wearing number nine.
Iain Henderson was moved out to allow Neil McComb to make his European debut.
Roger Wilson stepped in at number eight for Nick Williams, who is still recovering from a knee injury.
Castres: P Bernard, M Evans, S Bai, R Lamerat, M Garvey, R Tales, R Kockott; Y Forestier, M-A Rallier, A Peikrishvili, M Rolland, C Samson, M Babillot, P Faasalele, P Wannenburg.
Replacements: B Mach, S Taumoepeau, M Lazar, I Tekori, T Lacrampe, J Bornman, P Bonnefond, M Andreu.
Ulster: C Gilroy, A Trimble, D Cave, P Wallace, M Allen, R Pienaar, P Marshall; T Court, R Best, J Afoa, L Stevenson, N McComb, R Diack, C Henry (cpt), R Wilson.
Replacements: R Herring, C Black, D Fitzpatrick, I Henderson, M McComish, M Heaney, P Jackson, C Cochrane