Rockingham-Mandurah and Willetton fought out for a tie in a dramatic finish to their one-day clash at Lark Hill.
Batting first Willetton were in trouble at 7/121 after strikes from Leon Coombs, Aaron France and Ashley Blake.
An 80-run stand boosted the total above 200 as the Dragons were bowled out for 207 with late wickets to Aaron Burrage (3-25) cleaning up the tail.
The Mariners lost quick wickets struggling at 2/8 after both Callum Austen (2) and Teague Wyllie (0) were adjudged leg before wicket.
Burrage (46) combined with Corey Wasley (28) for a 54-run stand to get the home side back on track.
Quick wickets fell in succession and the Mariners slumped to be 6/124.
Craig Simmons smacked a quick fire 37 before being the second last man to fall with the score at 9/200.
Leon Coombs was the last man out for 16 and the Mariners were all out with eight balls remaining in the innings.
Rockingham-Mandurah are third on the first grade ladder after the opening three rounds and face Joondalup away from home next weekend.