Here's one to consider. It may sound wacky, but it works for me when I get those butterflies.
First of all, I think the worse thing you can do is to try to ignore the feeling. Rather acknowledge it, welcome it and think of it as the tingling that brings the power to win.
Consciously remind yourself that your opponent has this feeling but he has yet to embrace it as you have and while it is giving you strength, it is making him weak.
I also do this with those inner voices we get. Rather than trying to fight the confusion, I view the inner voice as my best friend. Someone trying to help me the best they can.
When I hear that voice, I'll stop. Get up, and listen to it. Discuss the inner self's thoughts amongst myself, so to speak.
I'm big on believing the mental side of this game is more influencing than the physical side.
In whatever way works for you, make positives out of what you are now interpreting as a negative. Don't fight the feelings, make them work for you.
While I'm rambling, I also do this with players who try to shark me while I'm shooting. You know, like wiggle their foot or move their stick from side to side while you are down on a shot right in their line of vision.
I see these sharks and (don't laugh) think of them as power hearts, (like in a video game) Now, this opponent has just sealed his fate by giving me super strength to make the tough shot.

This works much better than trying to ignore it.