Rockingham-Mandurah will need four wickets for a first innings victory on day two against Joondalup.
The Mariners won the toss and batted first and were in all sorts of trouble at 5/37.
Wicketkeeper James Bracey held the innings against top scoring with 70 and some late order hitting from skipper Craig Simmons who scored 46 from 58 balls saw his side to 184.
Joondalup looked comfortably at 2/90 after losing an early wicket before a wicket from Simmons and two scalps from Brandon Jacobs reduced the home side to 6/114 at stumps.
Day two begins next Saturday morning.