Giteau and Stephen Larkham were surprise guests at Brumbies training on Tuesday on the same day the club unveiled Andrew Walker as its wildcard for a pre-season tournament in Brisbane this weekend.

Giteau is back in Canberra after helping guide Suntory to the Japanese Top League championship last month and will stay in the capital in the off-season.

The Brumbies have strong ties with Suntory and are happy for Giteau to train with the Super Rugby squad before returning to Japan in the coming months.

Giteau left the Brumbies at the end of 2011 and has since had the golden touch, winning titles with French glamour club Toulon and Suntory, as well as making a Wallabies comeback for the 2015 World Cup.

The 35-year-old would have been a perfect man to slot into the Brumbies side for the Brisbane 10s for a potential showdown with close mate and NSW wildcard Drew Mitchell, but instead veteran Walker is stepping up for another comeback.

Walker, a dual international, turned heads last year when the then 43-year-old he made ex-Brumbies coach Larkham "half joke" about luring him out of retirement to help his injury-hit squad during the Super Rugby season.

It's hoped Walker will have the same impact again this year and even though he's another year older, forwards coach Laurie Fisher is expecting the same electric style that built Walker's career.

Walker played 47 games for the Brumbies, including winning the 2001 Super Rugby championship, and played rugby league for St George, the Roosters and Manly.

"They tell me that Walks was our best player last year, so I don't think it was a difficult decision to invite him back," Fisher said.

"He's still playing a bit of rugby league and touch football ... he's a fantastic addition to our squad. No [he hasn't trained with the Brumbies], we'll have a session up there on Thursday.

"To have a guy who has done a lot in the game is a great example, the guys really enjoyed playing with him last year and it will be no different this year."

The Brumbies will rest Christian Lealiifano, Scott Sio and Tevita Kuridrani for an extra week, but Chance Peni will make his Brumbies debut and young gun Rob Valetini will get his chance to impress.

The Brumbies are bracing for some fast-paced rugby as they prepare to go head to head with Fiji and the Canterbury Crusaders on Friday and the Wellington Hurricanes on Saturday.

Royals hooker Connal McInerney will play his second game for the Brumbies after being called in as injury cover for Folau Faingaa, while former Queensland No. 9 Isaak Fines has also been added to the squad.

The Brumbies want to play an up-tempo style this year in the hope it will help spark their attack, making the 10s a perfect platform for players to force their way into McKellar's Super Rugby side.

"We haven't spent too much time [preparing for the 10s], we'll put the jumper on and give our absolute best," Fisher said.

"It's an opportunity for guys to get minutes under their belt. It will test our scramble [defence], we'll see what our fitness levels are like and test our catch-pass skills and competitive instinct.

"Our volume and intensity has been very high. Sometimes you've got to try to keep a lid on it, the ante has definitely been lifted in the last 7-10 days."

BRISBANE 10s

Friday: (Men) Brumbies v Fiji at 6.09pm, Brumbies v Crusaders at 10.30pm; (women) Brumbies v Rebels at 5.11pm, Brumbies v Queensland at 9.32pm.

Saturday: (Men) Brumbies v Hurricanes at 4.33pm; (women) Brumbies v NSW at 5.31pm. Finals to follow.

Brumbies squad: Robbie Abel, Ben Alexander, Richie Arnold, Rory Arnold, Tom Cusack, Blake Enever, Mees Erasmus, Lolo Fakaosilea, Les Leuluaialii-Makin, Lachlan McCaffrey, Connal McInerney, FaaleleiSione, Darcy Swain, Rob Valetini, James Dargaville, Isaak Fines, Kyle Godwin, Jordan Jackson-Hope, Ryan Lonergan, Matt Lucas, Andrew Muirhead, Chance Peni, Henry Speight, Lausii Taliaulii, James Verity-Amm, Andrew Walker.

Brumbies women: Tania Afamasaga, Emerna Aviga, Kiahan Bell-Chambers, Kate Brown, Louise Burrows, Jane Garraway, Charlene Grubb, Jess Howard, Michaela Leonard, Irene Macarthur, Paremo Marsh, Shellie Millward, Georgia O'Neill, Michelle Perry, Darcy Read, Cecelia Smith, Merrin Starr, Remi Wilton.