Keane added: "The big danger for us is the opener against Cameroon. We know they're a decent side after winning a second African Nations Cup in February and they will demand respect."
"The Saudis will also be no mugs. If they can beat a South American team like Uruguay, then they too must be dangerous. We cannot take anything for granted."
McCarthy will not name his side for tonight until an hour before kick-off.
He lost Mark Kennedy to injury yesterday, as revealed in Standard Sport, and may give replacement Steven Reid a run from the start.