The Wallabies are confident superstar five-eighth Quade Cooper will recover from illness in time to tackle South Africa in Saturday night's Tri Nations opener at ANZ Stadium.

Cooper sat out Friday's captain's run as he battled flu and gastro but the Wallabies team doctor doesn't believe his condition is serious enough to prevent the playmaker from lining up for his first Test of the year.

Despite the untimely disruption to Australia's final training session before the big match, skipper Rocky Elsom said the Wallabies made the right call keeping their trump card rugged up inside while the relentless rain continued to bucket down in Sydney.

"If he's not feeling that well, it's best that he just gets better and feels better tomorrow," Elsom said.

"It was probably a good move not to train, but I think he'll be fine tomorrow."

Elsom was so confident Cooper - who later joined his teammates at lunch - would be on deck that he said a possible replacement in the Australian backline had not even been discussed.

In Cooper's absence from Friday's session, fullback Kurtley Beale and winger James O'Connor both ran at five-eighth with no other player joining the backline.

"It was alright. You've got to be able to deal with that," Elsom said.

Presuming he plays, Sydney's big wet may still prevent coach Robbie Deans from using Cooper at fullback in defence, a ploy that allows the fleet-footed star to trigger counter-attacks.

"Quade is a good enough player to be able to adapt to the conditions," Elsom said.

"He's no veteran, but he's played a fair bit so he'll know what he's doing, (no matter) where he's playing."

Brought to you by AAP © 2024 AAP