In a two-legged encounter finely-poised after a goalless draw at the John Smith's Stadium on Sunday, there is nothing to choose between the two sides.
And with the margins for success and failure minimal, the former Town striker and now club ambassador believes Wagner's tactical acumen could prove decisive.
Assessing where the game could be won and lost, Andy Booth said: “David Wagner could be the X-Factor and make the difference.
“He always seems to pull something out of the hat against the big teams so it will be interesting to see how he plays it.”
Many are tipping Sheffield Wednesday to progress to the Wembley final to face Reading FC after the draw away from home at the weekend.
But after spending five years at the South Yorkshire club, Booth knows exactly what to expect tonight from a sell-out Hillsborough crowd – as well as how to get under their skin.
“It's all to play for, they're probably favourites because of home advantage and it's a fantastic atmosphere whenever Hillsborough is full,” Andy Booth said.
“All the pressure will be on Sheffield Wednesday – their fans will be expecting to beat Huddersfield Town and it will be interesting to see how the side react to that.
“You would expect them to have a go at home, especially with some of the players they've got they should look to attack.
“That may leave gaps for us to exploit and if it's not going right at half-time their fans will certainly let them know.”