Gardner netted the winner in a 1-0 victory over the Welsh side in the first leg of their semi-final at Selhurst Park.
The former Tottenham defender told Sky Sports News: "Both teams came to win the game and it was a good cup tie. We'll get ready for the second leg now and hopefully we can go there and get a win.
"There's no reason why we can't. We are a very confident bunch of lads who have beaten some good teams along the way. We're looking to do the business there."