O'Connor, who was hospitalised after taking an accidental knee to the ribs in a heavy collision with Wallabies team-mate Berrick Barnes in Saturday's Super Rugby loss to the Waratahs, will not resume contact training for six weeks.
The Wallabies open their 2012 season with a one-off Test against Scotland in Newcastle on June 5 before taking on Six Nations champions Wales in a three-match series.
The 21-year-old could be available for the second Test against Wales in Melbourne on June 16 if his rehabilitation runs smoothly, however coach Robbie Deans is unlikely to take any risks with the 36-Test star.
Deans is also likely to be without Reds centre Ben Tapuai, who will be sidelined for three months after breaking his collarbone in Queensland's loss to the Stormers on Saturday night.
The 23-year-old, who made his Test debut against Wales in Cardiff in November, requires surgery and is highly unlikely to play any further part in the Reds' Super Rugby campaign.
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