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.
Gilbert has released a new line of rugby cleats. The Gilbert Virtuo 8S is part of the exciting new product. Check it out.
The Barbarians are one of the top invitational rugby sides with a long history and classic rugby jersey.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Lions get ready for their matches with this green training jersey. It's what the players wear. Get in the Gear!
A cool looking all black rugby cleat with the high performance adidas is known for. Get in the Gear!
Wear the crest of the British and Irish Lions on your t-shirt. A great look for the summer.
The Lions are ready to get their Australia tour underway. They arrive in Perth on Monday.
The New Zealand All Blacks training jersey for 2013/14. Get in the Gear!
The USA Rugby Pro Alternate rugby jersey is perfect for any fan of the Eagles. Get yours to wear during the summer Test matches.
The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.