O'Connor picked up a strain in the Rebels' 32-17 loss to the Reds on Friday and has been ruled out of his side's final two matches of the Super 15 campaign.
The 21-year-old utility back, who has played wing, full back, centre and fly-half for the Wallabies, has only just returned to action after missing his country's shock defeat to Scotland and their three-Test series win over Wales with a lacerated liver.
He will now be unavailable for the Rebels' two-match tour of South Africa but should be fit to feature in the Wallabies' opening Rugby Championship fixture with New Zealand on August 18.
Beale has not yet been ruled out of the games with the Lions and the Stormers but he hasn't yet travelled to South Africa after the Rebels admitted he is a definite fitness doubt despite not giving too much away about the nature or extent of his problems.
The former Waratahs star, who, like O'Connor, only joined the Rebels at the start of the season, will be reassessed on Tuesday after two days rest at home.
Beale missed the first three games of Australia's summer schedule after taking a heavy blow to the shoulder in the Rebels' defeat to the Hurricanes but he did return to the starting line up for the 20-19 victory over Wales in Sydney just over a week ago.
He picked up a rib injury early on in that game at the Allianz Stadium but saw out the 80 minutes and did the same for his franchise on Friday.