Yuffie smiles as she sees your still on the defensive, and moves to the side and kicks low in a sweeping motion to try to trip you, but doesn't finish it, instead as her foot is right before you she uses it to pull herself infront of you at the last second and try puching you from below.  Before all this you can see her not watching you but where your leg would be if she really tried to trip you, as if timing something.