Wallabies want to build five-eighth depth

Cooper, aged 34, faces a nine-month rehabilitation while O'Connor, two years younger, has also battled numerous soft-tissue injuries this year.

Noah Lolesio started at five-eighth in all three England Tests but the 22-year-old has been unable to fully cement himself in the role, with Rennie deciding they need to accelerate the development of other play-making options.

He felt they had built good depth at fullback and in the second row but competition at 10 was "the skinniest".

Waratah playmakers Tane Edmed and Ben Donaldson are in Rennie's sights.

"That's something that we're talking about, and we've got a few plans around that," Rennie said from Argentina on Friday.

"We've some good young kids coming through but not ready for this level yet.

"It's certainly an area of focus, we need to accelerate the development of young 10s."

There were reports 70-Test veteran Bernard Foley, who is 32, would return to the Wallabies fold but Rennie said no call had yet been made.

"We haven't made a plan around that, clearly at the moment we've still got three guys with Hodgey (Reece Hodge) covering and we'll reassess when we get home."

Rennie predicted Lolesio, who has missed selection for both Argentina Tests, would in time become a world-class five-eighth.

"He was disappointed in his third (England) Test but he's a good kid and I reckon he's going to be an excellent international 10, so he's definitely working hard on growing his game," Rennie said.

"We talked about connection, it's actually a strength of his at the Brumbies, but it wasn't as sharp. 

"He got deeper and deeper as the game went on and had to buy himself some time. 

"He's the type of player who doesn't have the leg speed of a Beauden Barrett so needs to be able to play flat but still get himself in a position where he can run, kick pass.

"He's played maybe a dozen Tests now, all against top teams, so he's played big games and will be better for it."