Northampton enjoyed plenty of possession at the Stade Pierre Antoine yet Castres defied their shaky start to the domestic season to stand firm in the face of heavy pressure from Jim Mallinder's men.
"We showed a lot of solidarity and we played for each other," said Capo Ortega.
"We never doubted ourselves as that's not how we do things. We just asked ourselves the right questions.
"We're only human beings, we make mistakes. We made mistakes last week against Brive, but we reassessed certain things, moved on and played at another level against Northampton.
"We're satisfied because, despite our problems in the setpiece, the team showed good spirit to get away with the win."
That spirit will undoubtedly be called upon next weekend when they travel to Ireland to face triple Heineken Cup kings and current Amlin Challenge Cup Champions Leinster at the RDS.
Capo Ortega knows improvements will have to be made for the Dublin showdown and he admits that progress has to be swift when it comes to their scrum and lineout.
"We played a solid game against Northampton but we will have to bring it to yet another level in Dublin next week," added the veteran Uruguayan.
"Our goal will be to produce the same performance in defence but, at the same time, to have a better setpiece to get possession.
"We had certain plans in the lineout against Northampton but they read it well. We're going to have to work on that.
"We'll have to hold the ball to build a good performance in attack, instead of watching the Irish like we did the Saints."