South Australia 228 and 238 for 5 (Sangha 55, Swepson 3-87) lead Queensland 398 (Labuschagne 159, Hearne 106, W Agar 5-88) by 68 runs

Alex Carey holds the key to South Australia's hopes of manufacturing a draw on the final day of their Sheffield Shield match against Queensland.

The Test wicketkeeper is the last realistic hope for the hosts, 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 238 for 5. 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 Mitchell Swepson dismissed him for 12.

Every other South Australia batter made a start, but so far Jason Sangha's 55 is the only half-century.

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 116-ball stay.

Earlier, Lachlan Hearne scored his maiden Shield ton as Queensland made 398 in their first innings.

They resumed at 319 for 6 and Hearne reached 106 before he was the eighth Queensland batter to fall.

McInerney bobbled the sharp chance at first slip off Wes Agar's bowling, but Carey took the catch to remove Hearne. It was Agar's fifth scalp of the innings, giving him his sixth five-wicket haul in first-class cricket.