After taking the competition by storm with five straight wins earlier this season, the SUNS will fall out of the eight if they lose at Metricon Stadium.
McKenna said Gold Coast would be treating it as a finals dress rehearsal and expected his team to be switched on from the outset.
He said the SUNS would be on high alert for the Cats' counter-attacking, led by superstar defenders Corey Enright and Andrew Mackie.
"They're well drilled and they're well coached," McKenna said.
"Sixty-one percent of their scores come from turnovers; they set up really well for turnovers.
"They almost give you a clearance to get it back off their half-back and counter-attack with the Enrights and Mackies of the world. Then it's their ability to spread through (Steve) Johnson, (Joel) Selwood and these blokes (that make them dangerous)."
Gold Coast is ranked third in the league for average clearances (41.2), compared to Geelong's 17th (34), and McKenna said they would have to be efficient from any advantage around the stoppages.
He said forward pressure would also be crucial, and that was one of the main reasons he had no hesitation in rushing Jack Martin back into the team after three months out with a shoulder injury.
Martin will be in the starting 21 and not be used as the sub.
"It's a reward for him and his hard work to get right," McKenna said.
"Bung shoulder or no bung shoulder, he tackles like I've never seen before.
"It's like a dress rehearsal for finals. If we're good enough to play finals, we've got to treat every game now like a final and that should be the mindset of our boys.
"If you do that you can actually start conditioning yourself for September, if you deserve to be there.
"Our young side like to rise to a challenge and this is one of the best going around, I reckon."
