Christian Lealiifano's hopes of a remarkable Test comeback will wait at least one more week with the Brumbies skipper one of six players heading home from South Africa early.

Lealiifano (shoulder), Scott Sio (adductor), Tom Robertson (ankle), Marika Koroibete (family) and Jack Maddocks and Rob Valetini (released for club rugby) are all set to return to Australia on Wednesday on the eve of the announcement of the Wallabies' first Test team of 2019.

Lealiifano and Sio are both expected to be fit to play in next week's Test against Argentina in Brisbane, but the news isn't so good for Robertson, who suffered an ankle injury in Tuesday's training.

Robertson was in the mix to play his first Test since August after suffering rupturing his ACL in Argentina last year, but he will have to wait until the first Bledisloe for the chance to return, likely to be ruled out of the Wallabies' Brisbane Test as well.

The departure of Robertson and Sio has opened the door for Waratahs prop Harry Johnson-Holmes to link up with the squad, joining James Slipper, Sekope Kepu, Taniela Tupou and Allan Alaalatoa.

Lealiifano has been playing through a shoulder complaint that he picked up late in the Super Rugby season and the flyhalf fell just short of being cleared to play in the opening Test.

Sio is in a similar boat to Lealiifano, with an adductor injury that he picked up in training, ruling him out of the first Test.

Koroibete will return home to be with his family after the birth of his second son last week, while Maddocks and Valetini will line up for their club sides in Sydney and Canberra, respectively.

The changes make the selection picture somewhat clearer for the Wallabies, who will name their team on Thursday night (AEST).

The Wallabies take on South Africa at Ellis Park, Johannesburg on Saturday July 20, kicking off at 5:05pm, Sunday 1:05am AEST, LIVE on FOX SPORTS and Kayo Sports.