The Tigers shut out Liverpool in their goalless draw at Anfield last week in their Premier League clash, but now face a different task against an in-form Saints side at the KC Stadium.
Agnew told the club's official website: "It will be a really tough game. Southampton are a possession-based team and very difficult to take the ball from.
"You have to be really organised against them and when you do get the ball, they are very quick to press and pressure you.
"Their position in the Barclays Premier League table reflects how well they are doing. Defensively we have been very solid away from home, but we now have a slightly different challenge because we are the home team this weekend."