Ireland coach Eddie O'Sullivan said his team's "mental preparation" had been the key to Saturday's 17-12 victory over South Africa at Lansdowne Road.
Horgan attempts to break clear of Van der Westhuyzen
"We prepared mentally very hard in the run-up to the game and it was more a mental battle out there than anything else," said a delighted O'Sullivan.
"We showed great resilience and we rallied very, very well when we were under pressure in the second half.
"It's difficult to put into words but I'm a very happy man to say the least."
O'Sullivan acknowledged that he was concerned for a period of the first half when Ireland were failing to turn dominance into scores.
"We weren't making our possession pay but when they came back at us we held firm.
"I thought we were really going to under pressure in the second half but we rallied very, very well.
"We knew that South Africa would go the full 80 minutes and we had to do the same.
"They are a big side and you could see at the end when they were running at us that it was taking a lot of toll.
"But our defence was tremendous and our defence coach Mike Ford got everything right and the forwards were outstanding as well.
"It was a great team performance. It wasn't pretty at times but it's not a beauty contest out there. It's Test match rugby."
Irish captain Brian O'Driscoll said the win was testimony to the intense physical work the squad had done over the summer.
"We worked so hard on our defence and we pinpointed what we felt were the Springboks' weaknesses.
"It is all credit to Eddie -- this was the best-prepared Ireland side I've ever been part of."
South Africa coach Jake White denied the Tri-Nations champions had under-estimated Ireland after their Grand Slam dream was shattered by the Irish.
White followed up the verbal assault he made on Irish rugby in June by declaring on Tuesday that only three of Eddie O'Sullivan's line-up - Brian O'Driscoll, Paul O'Connell and Malcolm O'Kelly - would merit a place in his squad.
But his unflattering assessment proved wide of the mark as Ireland clinched only their second victory over the southern hemisphere giants in 17 meetings.
"They are a great side who did well to beat
England at Twickenham in the Six Nations and they have beaten Australia in Dublin recently," said White.
"I knew it would be a difficult match and all credit to them for the way they performed.
"If this had been a trial game, then I would have selected all 15 Irish players for the real thing."
White said said his team had been undone by inexperience.
"We had so many chances, we just didn't finish them off," said White.
"One thing I can't understand is why we weren't more
The South Africans felt they had genuine cause for complaint over O'Gara's first half try after a quickly-taken tap-penalty.
Boks skipper John Smit said O'Gara was able to catch his side off guard because he had been told by the referee to talk to his players about a series of infringements.
"I turned my back to talk to them and when I turned round he was diving over the line.
"Considering we lost by five points, you could say I'm quite angry, yes."