The head coach is acutely conscious of his third-placed side’s last two away results in the Championship.
His team showed susceptibility to set-pieces - and area in which fourth-bottom Cardiff are strong.
“We cannot close our eyes to the facts,” said Wagner, whose side have claimed three wins on their travels this term while Cardiff have suffered five home defeats.
“In our last two away games, we conceded eight goals, six to set-pieces.
“They have scored 14 goals, 11 from set-pieces, which says everything about their strength. We must make sure they can’t use this strength.
“We must avoid stupid, sloppy mistakes, don’t give set-pieces away too easily.
“When we do give one away, we must defend in a very focused way with all our energy.
“A clean sheet would be a big step in the right direction for us.
“With our offensive play, we can create some moments where we hopefully can be clinical.
“We have to go away and perform in our identity.
“We want three points and there is no reason why we can’t get them if we are at our highest level.”
Wagner is looking forward to pitting his wits against former Town manager Neil Warnock.
It’s a sixth match at the helm for the 67-year-old, who was appointed to succeed Paul Trollope on October 5.
He took seven points from his first three games, but the Bluebirds have lost their last two.
“For sure Neil Warnock is a big character in British football,” said Wagner.
“The ball will probably be in the air as much as it is on the grass. There are few secrets with his teams.
“But we are in a position in table where we can have trust and self-belief, and we want to win this game”