South Perth are in a strong position against Midland-Guildford at Lilac Hill.
New recruit Cam Huckett and giant quick Alex Bevilaqua kept the home side at bay, taking wickets at regular intervals, with Tim Armstrong the only batsman to show fight.
Huckett claimed three wickets as the hosts finished 9-146. Two early wickets from Armstrong have kept his side in the hunt as the Sky Blues went to stumps at 2-32.
Trent Ovens (27n.o.), who starred in last week’s run chase win over University, holds the key for South Perth when play resumes next Saturday at 11.40am.
Elsewhere, league leaders Perth are in danger of their first defeat of the Premier Cricket season after a poor first day against Claremont-Nedlands at Fletcher Park on Saturday.
In the first of the two-day fixtures, Perth were bowled out for 181 inside 53 overs, with Sean Roberts making a crucial half-century after the Demons were in serious trouble at 8-109.
The Tigers had 30 overs to face late in the day and moved to 1-78 at stumps to be within 104 runs of first-innings points.
Australia under-19 international Liam Guthrie took the only wicket for the Demons.