A five-wicket haul from Leon Coombs has put Rockingham-Mandurah in the box seat for victory against Bayswater-Morley.
The Mariners batted first and were all out for 188 wicketkeeper James Bracey top scoring with 45 while Aaron Burrage contributed with 42.
Rockingham-Mandurah knew that needed quick wickets to put the home side on the back foot and Coombs and Adam France delivered.
France dismissed Aaron Todd for 1 before Coombs cleaned up the next four.
Burrage picked up the fifth dismissal for one more from Coombs collected his five-wicket haul.
Bayswater-Morley were 7/53 at stumps setting up an exciting day two and the possibility of an outright result on Saturday.