Victoria 195 for 7 (Harper 68*, Manenti 4-66) trail South Australia 307 (Hunt 62, Scott 53, Siddle 3-57) by 112 runs

Ben Manenti has masterminded a 4 for 7 collapse to spin South Australia into a strong position at the halfway stage of their Sheffield Shield match against Victoria at Adelaide Oval.

The offspinner was the central figure behind the visitors' 45-delivery collapse from 59 for 0 to 66 for 4 in the middle session, before wicketkeeper Sam Harper saved his side from embarrassment, joined in the middle late in the evening by Peter Siddle.

Manenti had Jonathan Merlo caught at backward square leg by Lloyd Pope, before bowling Ashley Chandrasinghe, then taking a sharp catch at second slip to dismiss Campbell Kellaway. Manenti dismissed Peter Handscomb, squeezing a catch to Henry Hunt at short leg, and added Tom Rogers to his list, miscuing a pull shot to Pope at backward point.

Victoria captain Will Sutherland feathered a catch to wicketkeeper Alex Carey, as did Mitchell Perry, Liam Scott striking immediately with the second new ball.

Harper, who has looked in decent touch, remained the key scalp for SA.

In the corresponding fixture last summer, Harper thumped nine sixes in an astonishing 151 off 109 balls to lead Victoria to a thrilling, low-scoring victory.

"We've still got to get these last three wickets," Manenti said after stumps on Saturday. "Harps is batting nicely and Sids has been around for years - he can obviously chip in as well.

"Get these last three, then get to work with the bat and give ourselves a real good shot tomorrow afternoon or early day four to have a crack and put ourselves in a position to win it."

After resuming at 286 for 9 overnight, SA's stubborn tail frustrated the Victorian attack on the second morning before their innings concluded when No.11 Pope, who scored a personal-best 17, edged Cameron McClure to Harper.

Evergreen ex-Test quick Siddle, who turns 40 this month, was the pick of Victoria's bowlers, capturing 3 for 57.