That means daily breakfast deliveries, perfectly brewed lattes, and the best part? Making every player in the backline do their gym sessions while wearing nothing but budgy smugglers.

It might seem like an unusual way to celebrate a double 100-Test milestone, but Drew Mitchell revealed it is Giteau's way of turning his personal accolade into a bit of fun.

The Wallabies will put century celebrations for Giteau and captain Stephen Moore on hold as they put all of their energy into a World Cup quarter-final battle against Scotland on Sunday (Monday morning AEDT).

It is a rare feat in Australian rugby and behind the scenes Giteau has been lapping up some teammate love as he reaches an unlikely ton more than a decade after his debut.

"It's called the 'Hundy week' so if Gits asks for anything, he gets it. Which he is kind of now taking the piss a little bit," Mitchell grinned.

"Guys will just get themselves a coffee and he'll say: 'I will have that, thanks'.

"He'll say to Bernard Foley: 'I will have porridge with banana, oats and raisins' or whatever, and off [Foley] goes to get it. Little things like that, you just can't say no.

"Yesterday he had us in the gym just in our tights. No shirts, no shorts, just because he was doing it on the exercise bike."

Giteau and Moore will become just the seventh and eighth Wallabies players to reach the 100-Test mark.

It puts them among Australian rugby's elite, joining World Cup winners Stephen Larkham, George Gregan and David Campese as well as Nathan Sharpe, George Smith and Adam Ashley-Cooper.

Both have admirably played down the moment this week in multiple interviews, preferring to focus on a do-or-die match against Scotland.

Both are playing in their third World Cup and it is likely this will be their last chance to win one.

Giteau and Moore will finish their careers as two of the Wallabies' most decorated players, but they desperately want team success.

Giteau played in the 2003 final defeat and was there when England bundled Australia out in the 2007 quarter-final.

His Test career seemed all but over, stranded on 92 Tests when Robbie Deans snubbed him from the 2011 World Cup squad and Giteau moved to France to play for powerhouse Toulon.

But his second chance came when the Australian Rugby Union changed its eligibility rules to allow overseas-based players to be available for Wallabies selection.

Thirteen years ago Giteau was the fresh-faced rookie who carried a stuffed wallaby to Buckingham Palace as the youngest member of the 2002 squad.

Now his teammates are delivering lattes and adhering to his dress code out of a sign of respect.

But Mitchell says that is his Toulon teammate's way of brushing the spotlight and attention. Sort of.

"Yeah, he's playing it down. That's how he'd prefer it – to approach it more on the jovial side and try to brush away any accolade about it, or seriousness," Mitchell said.

"That's kind of the way he likes to go about it. But again, speaking to him and knowing him as I do, it is something he will look back on as opposed to rubbing it in our faces."

Giteau and Mitchell will return to Toulon after the World Cup. Neither has considered what their Wallabies future will be, and whether they will wear the gold jersey again after the World Cup.

Mitchell, 31, baulked at the idea he could have a chance to join Giteau and enjoy his own "Hundy week".

But he is yet to contemplate whether he will extend his 67-Test career beyond the end of his third World Cup campaign.

"It's not something I have considered, I didn't even think I'd be here so I don't know if I have thought too much about after this," Mitchell said.

"But I have loved the opportunity and I have always cherished the opportunities I have got in this jersey. One thing that needs to hold up is the body, two is the form, and three is the coaches who want to bring you back. We'll see how it goes."

WORLD CUP QUARTER-FINAL

Wallabies v Scotland at Twickenham, Sunday 4pm (Monday 2am AEDT).