The Magpies had won nine games in a row in all competitions before being beaten by Blackburn Rovers two weeks ago, but Rafa Benitez's men have lost their last two league games and exited the EFL Cup since then.
And, although the cup defeat came after a penalty shoot-out against top-flight opposition and last week's loss at Nottingham Forest was influenced by two controversial red cards, Birmingham boss Rowett reckons he has spotted a chink in Newcastle's armour.
His Blues side travel to St. James' Park for a 3pm kick-off on Saturday and, speaking to bcfc.com, Rowett said: "We want to go there and give Newcastle something to think about.
"We've seen in recent games that they're just a team; a good team, we're really respectful of their players and how they play, but they've shown that they do have some faults in the team themselves and that they can be beaten.
"But what you also have to do is look at the strengths of your own team and how you think that you can play against it. Usually we're quite suited to teams that pass the ball, we're quite suited to teams that want to play expansive football. We don't mind that. That's something that fits our style and that we negate quite well.
"But of course, when you've got very, very good players on the pitch - the likes of (Matt) Ritchie, the likes of (Aleksandar) Mitrovic, even in the lack of space they can still cause you problems because they've got that technical ability. But we know what we have to do.
"We'll make sure that the players know that we've won games like this, we've caused teams problems like this. You look at last season, we drew at Burnley, we beat Derby County away, we drew at Middlesbrough; a couple of seasons ago at Bournemouth we were 2-0 up against a side that romped home with the league (Birmingham went on to lose 4-2), so we certainly won't be fearful of it.
"I'm looking forward to the game but we know we're going to have to be at our best, energy-wise and the way we look after the ball, when we get the ball."