The visitors’ Chris Chellew was impressive, as he smashed an unbeaten century to guide his side to 9-254 over Wanneroo’s 140 at Kingsway Sporting Complex.
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He proved himself the competition’s clear stand-out all-rounder as he and Joel Crosswell batted the Roos out of the fixture.
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READ NOWMatt Dzodzos was the best of the Wanneroo bowlers with 4-58, before the hosts again found themselves in trouble with the bat in their second innings.
Fremantle’s Jamie Heath ripped through the top order to collect four wickets and eight for the match.
The Roos narrowly avoided another outright loss, finishing 8-88, with Englishman Dan Lawrence top scoring with 31.
The Port Boys stay in second position, hot on the trail of league leader Claremont-Nedlands.
The Roos (12th) have a big opportunity for victory in the upcoming round against 11th-placed Willetton at Burrendah Reserve.