When the Lions headed to South Africa in 2009, the suggestion that they wouldn't be encountering Giteau in 2013 was almost unthinkable. But speculation over the last few weeks that the 28-year-old would miss out on a World Cup spot has meant today's decision was not unexpected.
The Brumbies playmaker, who heads to big-spending French side Toulon next season, missed out to Pat McCabe and Berrick Barnes after the former took his Test place in the Tri Nations and the latter recovered from concussion to win a spot in the 30-man party.
"Thank u ballboys, thank u linesmen. That's it," Giteau tweeted before Robbie Deans made his official squad announcement in the early hours of this morning.
"Really wanna thank everyone for the support. Was a huge honour to get the chance to represent my country as often as I did."
Giteau won a total of 92 caps after making his debut back in 2002, a year after the Lions last visited Australia.
The former Western Force star scored 684 points and was one of his country's most consistent performers during his time in gold and green.
He featured at scrum-half, fly-half and centre during his stellar Test career but the emergence of Quade Cooper, Will Genia and now McCabe has seen him deemed surplus to requirements by Deans and assistant coach fellow Jim Williams.
The decision to omit Giteau from the global gathering in New Zealand next month has been met with criticism from a number of high-profile former Wallabies, including ex-captain Andrew Slack who believes a clash of personalities rather than any playing reasons may be behind the controversial call.
"I can't see any reason why he wouldn't be picked. It's got me flabbergasted," said Slack.
"If they don't get on, one of them needs to grow up. If that is the issue, then that's a real shame because at the end of the day, the only people who end up paying for that is everyone else.
"Talent, experience, class, versatility and healthy - they are five compelling factors to select Giteau I would have thought."