Though Ospreys are guaranteed their place in the top-four, the cherry of attaining a home semi-final is on offer at the Sportsground.
And the magnitude of the task is not lost on Lam.
"We will need our best attack ever and our best defence," Lam told the Galway Advertiser.
"We scored tries against them last year, but they scored more. Their attack is lethal, so we need to make first-up tackles to stop them getting behind us.
"They are the number one side for a reason. They have quality players, British Lions and Welsh internationals.
"We are under no illusion of the challenge we face, but when the pressure comes on we must trust in our ability and the team."
Follow us on Facebook, join the conversation on Twitter, sign up to our YouTube channel for extensive match highlights and sign up for our newsletter for regular updates on the GUINNESS PRO12