Bernard Laporte admits he thought Toulon would lose their Champions Cup semi-final when Ali Williams was sin-binned in extra-time.
The two-time European champions made a third straight final with a 25-20 win over Leinster, but were pushed all the way in Marseille.
Williams was sin-binned late in the first half of extra time with the scores level at 15-15.
However, rather than buckle, Toulon reacted with a Leigh Halfpenny penalty followed by an interception try from Bryan Habana, which ended up proving decisive as they set up a final against Clermont in a fortnight.
"We showed a lot of heart, desire and enthusiasm. That's the cement of the team. The players have that, despite their advanced age for some. No-one gave up, but when Ali (Williams) went off, I thought we'd lost," Laporte told the EPCR website.
"And that's where we won it. I told them all week that it won't be the team that scores the most tries that will win, it's the team that makes the fewest mistakes. I need to single out Leigh (Halfpenny) and Bryan (Habana, who weren't good, they were great. The best players don't have off-days in these sorts of games.
"Congratulations to the players, to the team. We weren't at our best, there was a lot of nervousness, a deficient lineout but also a lot of enthusiasm. The paradox is that we won with 14 players. If we'd bee more relaxed, we'd have won by more. But we weren't accurate, we made too many handling errors."
Laporte had earlier made the decision to remove Freddie Michalak early in the second half, to the fly-half's obvious frustration, but the former France boss felt he made the right call.
"I stay focused on the interest of the team. I have to make decisions in difficult moments. I take responsibility," he added.
"For three days he's been in pain in his knee, a small oedema. I felt he was hesitant. I thought he must be in pain. His kicking game wasn't great, he wasn't at 100%. I thought he was disappointing today, but everyone has bad games."