The R's currently sit second in the Championship table, four points above Derby, who Redknapp believes could earn promotion to the top flight.
"Derby are genuine contenders for promotion," QPR's Twitter page quotes Redknapp as saying. "There's about six or seven teams that are in the shake up for promotion.
"[They] are a big, big club. They've got a great new stadium. We played well against [them] at Loftus Road. We edged that game, but we know this will be very tough on Monday night."
QPR are 10 points adrift of Championship leaders Leicester City.