Genia limped off during the victory, Australia's first of the Rugby Championship, and he follows regular captain James Horwill (hamstring) and his initial stand-in David Pocock (knee) on to the sidelines for the rest of the Southern hemisphere competition.
The 24-year-old's knee was strapped with a large ice pack and he required crutches to walk after the match in Perth. Scans on Sunday revealed he had ruptured the anterior cruciate ligament, a team spokesman said.
Local media reported he will be replaced by Brett Sheehan in the Wallabies' squad for their clash with Argentina next week on the Gold Coast.
