Rockingham-Mandurah face an uphill battle on day two of their match against South Perth at Richardson Park.
South Perth won the toss and batted first on the opening day and posted 272.
Aaron Burrage and Leon Coombs claimed three wickets each for the Mariners while Ryan Done returning to first grade contributed with two.
The chase started poorly for Rockingham-Mandurah losing three wickets in the six overs they needed to see out before stumps.
Tyler Robertson (0), Kane Standing (4) and skipper Ed Pollock (0) were all dismissed.
The Mariners were 3/17 at the close of play.