Jordan Uelese

Uelese was ruled out of the Wallabies' June Series on Sunday, with suspicions he had suffered the serious injury, and scans on Monday confirmed the worst-case scenario.

The 21-year-old was on the field for just 10 minutes in the Rebels' win over the Blues in Auckland before falling awkwardly in a tackle on Blues no. 8 Akira Ioane.

Uelese will go under the knife on Thursday, and begin the long rehabilitation process.

Rebels general manager - professional rugby - Nick Ryan, said the news was a blow to the team.

Cheika has made four changes to the Wallabies starting side for their match against the Springboks with hooker Tatafu Polota-Nau, prop Sekope Kepu, second-rower Adam Coleman and winger Reece Hodge all returning. 

Named on the bench, Melbourne Rebels rookie hooker Uelese is in line to make his test debut despite having played less than half an hour of Super Rugby. 

Many will see it as a gamble against a formidable Springboks pack, but Cheika is hellbent that Uelese, a standout at U20 level, is made of the right stuff.