The D2 reserves lost the preliminary final by nine points to Whitford on Saturday but the Warriors have since been disqualified for playing an unregistered player.
Now the Cougars will play Wembley in the grand final at Richard Guelfi Reserve in Balcatta this Saturday.
“The boys are ecstatic to be given a second chance at playing in a grand final,” club spokesman Brad Woodgate said.
“They are looking to make the most of their opportunities and improve on last week’s game.
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READ NOW“It’s the club’s first grand final since winning the B grade premiership in 2013, and we are looking for a successful outcome again.”
Woodgate congratulated Ben Bowness for winning the league’s division two best and fairest award.