Gardner has warned his former club Villa they should be looking over their shoulder after the upturn in fortunes of Blues under manager Alex McLeish.
The midfielder left Villa in January to join his boyhood heroes after becoming frustrated at the lack of first-team opportunities under then manager Martin O'Neill.
He is relishing playing regular football and is Blues' leading scorer this season with four goals.
Gardner told Press Association Sport: "We're the underdogs at the minute. Villa have been the top team for the last few years.
"Now we're moving up the table and doing well every week. Last season we finished really high and we're looking to improve on that.
"Villa are looking over their shoulders now, and so they should be. There is the potential to become the city's top team. I'd like Villa to be underdogs and Blues to be above them. Time will tell won't it?.
"But it would be amazing if we did finish above them this year because then we could give them six or seven years of stick all in one year.
"They're a top-class team. We're not going there thinking we'll walk over them because they've got players missing.
"We know it's going to be a tough game and we're going to get in their faces and make it hard for them. We'll run our socks off for 90 minutes and hopefully get the points."