Both teams are coming into the big match on the back of good performances. Saints put six tries past third-placed Bath last Saturday, with Harlequins earning plenty of plaudits for the way they played against Exeter at Twickenham.
And the Samoan says in this week's Saints podcast that Harlequins can be dangerous given the opportunity.
"You do your homework on different teams, and they all have their strengths," he commented. "The way that Harlequins play is pretty dangerous, and if we let them get their front foot ball it could be dangerous for any team that they play against.
"They're a quality side with some quality players and defensively we're going to have to be on our game.
"It's going to be a tough challenge, but we're looking forward to it. We're not just mauling or scrummaging; we're getting players across the field and being a threat in attack and are putting teams under pressure defensively."
A few hundred tickets are still available for Saints versus Harlequins, but they are selling quickly and early booking is recommended. Ordering tickets online could not be simpler – whether you are on a desktop, laptop, tablet or mobile just CLICK HERE and follow the straightforward instructions!
You can choose your seat, and [email protected] to beat the queues and save yourself the admin fees!
And you can hear the full interview with Kahn Fotuali'i in the official Saints podcast, which will be available on SoundCloud later this week!