Rockingham-Mandurah have pulled off one of the biggest victories of the season chasing down 301 to defeat Scarborough.
Callum Austen smashed 54 not out from 47 balls including six fours and a six to be there at the end with Ronan Hogarth who was not out 11.
The Seagulls posted 7/300 from 50-overs after some inaccurate late over bowling from the Mariners letting the total reach more than predictions.
Craig Simmons claimed two wickets and was the only multiple wicket-taker.
Rockingham-Mandurah lost two early wickets in the chase to fall to 2/33 a strong 97-run stand from Teague Wyllie (55) and Corey Wasley (59) steadied the ship.
More middle orders partnerships from Damien Burrage and Nathan Hutchinson who put on 68 and then Austen and Sam Day (16) got the Mariners in striking distance.
Austen stood strong to claim the victory for the home side to cement themselves in second spot on the ladder.