The absence of Wallabies flanker Lukhan Tui on tour to Africa and Argentina could be compounded with backrower Pete Samu also under an injury cloud.

Samu has been in Canberra this week and Australia is still waiting on the results of scans on a knee injury suffered against the Pumas. The rookie Wallabies forward came off the field in the second half.

There is yet to be a call made either way on Samu but with the Wallabies' South Africa-Argentina tour beginning in just four days, there is an urgent question mark hanging over his fitness.

Wallabies coach Michael Cheika is set to name the squad on Friday, and with Michael Hooper having also missed the Pumas Test with a hamstring injury, he is facing headaches right across his backrow.

Samu came off holding his knee after 43 minutes against the Pumas, before being replaced by Ned Hanigan.

The flanker was parachuted into the starting team in Brisbane after the late withdrawal of David Pocock and was again a last-minute starter on the Gold Coast with Michael Hooper (hamstring) ruled out.

Only time will tell if Hooper can fully shake off a recurrence of the hamstring issue that forced him out for the final month of Super Rugby, though Cheika was confident after Saturday's game that the skipper would be joining the team on tour.

Tui's chances of being on the plane appear slim after the sudden loss of his stepfather last week and the fall out of an ugly post-match altercation between the Reds forward and a Wallabies fan.

The 21-year-old was involved in a post-match scuffle with a fan after Australia's shock loss to Argentina and subsequently told teammates he was planning to take time away from the game. Cheika said on Sunday the rookie was unlikely to make the trip to South Africa.

Queensland's Caleb Timu would likely be the next backrower to step into the team should there be an absence, with the no. 8 the spare loose forward in Australia's squad in recent weeks.

If Michael Cheika has to look beyond that, the NRC has showcased some in-form backrowers and that could open the door for another Wallabies debutant or a return to some of the capped players plying their trades in the provincial competition.

Melbourne's Angus Cottrell has been on the Wallabies radar before and his combative form with the Rising so far in the NRC would not hurt his prospects should a spot need to be filled.

Queensland forwards Liam Wright and Adam Korczyk have also trained with Wallabies squads in the past year and could shape as outsiders for a call-up.

Melbourne's Richard Hardwick, Sydney's Will Miller and Chris Alcock, from the Western Force, have all been in excellent form as well.

Sydney flanker Jack Dempsey was one of Australia's breakout Test stars last year and made a promising return from injury against Brisbane City, but the 24-year-old is being meticulously managed after nearly a year out of the game.

Dempsey played just 31 minutes against Brisbane in what was his first outing nearly 11 months after suffering a hamstring injury against the Barbarians.

Australia's squad for the two-week tour will be named on Friday, ahead of the team's Saturday departure for Port Elizabeth.

The Wallabies take on the Springboks in Port Elizabeth on Saturday September 29, kicking off on Sunday September 30 at 1:05am AEST, LIVE on FOX SPORTS.