Grimus was leading the first final when he was muscled out of position and after regaining balance, he gave himself an opportunity to finish in the first two places, which was needed to advance to the next round, when he fought back towards the front of the pack.
Unfortunately Grimus lost further ground when he ran wide on a turn and was unable to recover.
Grimus finished the day in 23rd, behind winner David Duncan from Canada, while Austrian Andreas Matt was second and Germany’s Daniel Bohnacker was third.
The women’s event was won by Swiss skier Katrin Mueller, Canadian Marielle Thompson was second and German Heidi Zacher was third.
Kennedy-Sim was 27th while fellow AIS / NSWIS athletes Katya Crema was 34th and Jenny Owens was 36th.
The fifth squad member, Scott Kneller, did not compete due to suffering concussion and a back injury in training before the qualification session.
Kneller was taken to the Bolzano Trauma Centre in Italy, 270 km from Milan, where he is expected to remain for at least another 24 hours for further observation.
AIS ski cross program head coach Matt Lyons said that he expects Kneller to make a full recovery but he is likely to miss four to six weeks of competition.
Lyons said it was too early to say if the injury would rule Kneller out of the Sochi Olympic Winter Games in Russia in February.