Missed the veto, but the maps are Cobble, Cache, Inferno.
NiP played Cobble 3 times; vs Epsilon, C9 and LDLC. They lost vs Epsilon 16-6, and beat C9 and LDLC 16-14. Fnatic played Cobble vs IBP and they won 16-7. Some Fnatic know NiP's tactics. They definitely saw their matches and they know how they move. Then again, if Fnatic didn't practice it a lot, then their smokes might not be on point.
Cache. Well, NiP think they are decent at Cache, but they don't generally win vs good teams. Fnatic play it even less, so their starts might not be on point.
Inferno...well, I don't know. I want to favor NiP lost their last 7 inferno matches, but generally they are quite good. Fnatic didn't loss in the last 11 matches on Inferno (1 draw). If it comes to the last map, Fnatic SHOULD start favorites.