Knauß tested positive for the anabolic steroid Nandrolone at a World Cup downhill in Lake Louise in Canada on 27 November 2004 and was subsequently given an 18-month ban from sport.
The incident involving Knauß and the banned substance Nandrolone occurred during a World Cup downhill event in Lake Louise, Canada on 27 November 2004, resulting in an 18-month ban from participating in sports due to doping regulations.