Toulouse coach Guy Novès, who has led his side to four Heineken Cup successes believes mental strength saw the reigning Champions through their quarter-final clash with Biarritz Olympique.
The game at Estadio Anoeta was taken into extra time as Biarritz fought their way back from 17 v 0 down at half-time to level the scores 17 v 17 after 80 minutes.
A late try from Yannick Nyanga won the game for Toulouse and set up a rematch of last year's semi-final with Leinster.
"Mental strength, mental strength, mental strength. That's what takes over from strategy and physical prowess," he said.
"We needed to believe and to really want it.
"I wouldn't dare say it was experience considering the youngsters that played.
"It was the collective experience of Stade Toulousain that allowed us to snatch victory away from home. With all the respect I have for Biarritz, I think we deserved the victory.
"Against a team of this quality we showed enormous selflessness and will to succeed.