The Test wicketkeeper is the last realistic hope for SA, who lead by 68 runs with five wickets in hand at Adelaide Oval.
The run out of Jake Lehmann in the last session was disastrous and the hosts went to stumps at 5-238. Carey is 37 and Liam Scott has made 20.
Lehmann hesitated when he went for a quick single and a sharp throw by substitute fielder Hugh Weibgen to bowler Mitch Swepson dismissed him for 12.
Every other SA batsman made a start, but so far Jason Sangha's 55 was the top score.
Swepson bowled superbly to take the first three wickets. The spinner trapped Henry Hunt lbw for 26, breaking up the opening stand of 57.
He then bowled opener Conor McInerney for 46 and Usman Khawaja took a sharp chance at slip to dismiss Nathan McSweeney for 26.
Michael Neser found the gap between bad and pad to bowl Sangha, who hit four fours in his 114-bowl knock.
Earlier, Lachlan Hearne scored his maiden Shield ton as Queensland made 398 in their first innings.
They resumed at 6-319 and Hearne reached 106 before Hearne was the eighth wicket.
Conor McInerney at first slip bobbled the sharp chance off Wes Agar's bowling, but Carey took the catch to remove Hearne.
The Queensland No.5 hit 12 fours in his 143-ball innings. Marnus Labuschagne top-scored with 159 - ensuring he is in the first Test team calculations - and Agar snared 5-88.
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