In the first round of two-day fixtures, Willetton put themselves in a dominant position at stumps on day one having already taken first innings points.
After Dragons captain Matt Johnston sent the visitors in to bat, Aaron McCall ripped through the Mariners batting lineup with five wickets, bowling unchanged with the skipper for majority of the innings.
Only Brayden Sutton (18) and Mitch Green (26) were able to get past double figures in a disappointing outing for the away side who had been 2-45 before losing 8-21 in a horrible stretch.
McCall finished with figures of 5-22 from 14 overs, while Johnston took three wickets.
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READ NOWThe Dragons went in search of quick runs scoring 83 from just 22 overs with the loss of three wickets, taken by Craig Simmons, Brendon Diamanti and Kyle Gardiner.
Englishman Liam Livingstone (30) and James Godfrey (35) entertained before the hosts chose to make an early declaration in search of an outright win.
Rockingham-Mandurah finished the day 1-29, 12 runs ahead of the Dragons and face an uphill battle to avoid outright defeat.