for sure, but its not life or death for fnatic. i think with this lineup they've really worked their mentality. never taking small teams for granted (proved by the minor). they also fight every time which will be proven by this game hopefully.
it come down to map difference between the 3 tied teams for #2 and 3 spot. If fnatic lose they have beaten astralis and mouz which are the other teams who would be tied in points if astralis beats mouz today.
Navi lost to mouz but won vs astralis so it would come down to map difference between mouz navi and astralis if astralis beats mouz and fnatic beats navi