Western Australia's seamers have given the visitors the upper hand on day one at Adelaide Oval, leaving South Australia's hopes of beginning afresh for the second half of the Sheffield Shield season endangered.
The Redbacks reached 5-209 at the end of the second session with four batsmen having made starts for the home side so far.
Opener Jake Weatherald top-scored with a boundary-laden 60, before he was caught at second slip just after lunch off David Moody (2-36).
Will Bosisto soon went the same way, only for Tom Cooper (33 not out) and Harry Nielsen (44 not out) to counter-punch for South Australia with an unbeaten 66-run stand.
Earlier, SA were reeling at 2-25 early on with the usually reliable Callum Ferguson making a four-ball duck as Matthew Kelly (1-58) made an important breakthrough.
Joel Paris (2-36) picked up opener Henry Hunt (11) and then Travis Head (46) in his second spell.
Test batsman Head looked polished in his 62-ball seven-boundary innings, before he was caught behind for one of Josh Inglis's three catches.
With just one victory from six outings, SA need to win the match if they are to stay in touch with second-placed WA.
Australian Associated Press