Giteau celebrated his 100th cap with a man of the match performance in Sunday’s controversial 35-34 victory over Scotland and now faces a semi-final appointment with Argentina at Twickenham.
The 33-year-old has benefited from coach Michael Cheika’s demand to the Australian Rugby Union that they reverse a long-standing policy by allowing him to pick overseas players if they have made 60 or more international appearances.
It has lured Giteau away from his Test exile at Toulon where he has been magnificent since his shock exclusion from the Wallabies’ 2011 World Cup squad.
“I never thought I’d be playing in a World Cup semi-final a year ago,” Giteau said.
“I thought I’d be doing a couple of speaking gigs to get a bit of cash. That was the plan but it’s just been an amazing ride for me this last six months.
“We showed a lot of character at the end against Scotland. Personally, I’m just happy we survived another week.
“The 100th cap was good, but the man of the match award I think should have gone to someone else in our team.
“We take a lot from the way we regrouped, how calm we were when they scored a try with only four or five minutes left.
“We were able to get down their end and apply pressure. We took a lot of confidence out of that.”
Giteau will duel with Toulon team-mate Juan Martin Hernandez when Argentina attempt to reach the final for the first time on Sunday.
“Juan is a beautiful man – I’ve always told him that at Toulon. He’s very skilful, he’s tough, defensively strong and adds a lot of stability to that team,” Giteau said.
“I know what it’s like to play with him, especially in big games. He is a very, very good player.
“He’s very confident in what he does and the things he can do a lot of other players can’t.
“Argentina are very good at every World Cup. Whatever they do, they always seem to peak in these tournaments. They’re incredibly dangerous.
“We’ve seen what they were able to do to Ireland and how far they pushed New Zealand in the first game. Every round they’ve been really good. They’ve blown teams away quite easily.”
Meanwhile Argentina’s Nicolas Sanchez picked up useful hints from former England fly-half Jonny Wilkinson and Wallaby centre Giteau at Toulon which he hopes can help him steer Argentina to a Rugby World Cup semi-final victory over Australia on Sunday.
Sanchez has been superb in dictating the Pumas’ attacks at a tournament in which they have scored 26 tries in five matches. He has notched 74 points and starred in Argentina’s 43-20 quarter-final win over Ireland. “If you ask me who has been the best rugby player ever, I’d say Wilkinson and to have been next to him was spectacular and I tried to make the most of that,” Sanchez said.
“Giteau is a world-class player who attacks well and makes good decisions.”
Overall the Pumas are feeling calmer than in the build-up to Sunday’s clash with Ireland in Cardiff but the butterflies would come as they prepared for the biggest challenge of their lives.
“We must do what we did against New Zealand, win our one-on-ones and the breakdown and not commit penalties because if we do, Australia will choose to go for a lineout where they are very good,” Sanchez warned.