On the other hand, she's still human. She still need to breath, still subject to the air. You put a lot of pressure on her, and you're guaranteed to affect her. This will make dodging her attacks easier at the very least. At best? This can instantly knock her out. Divers had been known to pass out at certain deepness, thanks to the pressure the body and brain is subjected into. The air pressure will have an effect on her, it will weaken her, lower her accuracy and defense, so to speak.
The only thing we need to remember is to take care of lowering the air pressure little by little once we're done, as well as finishing the fight as fast as we can. Because decompression sickness can be lethal, after all, if you keep the pressure for too long and decompress the pressure too fast. (Sources: What-if xkcd, Ever17, and wikipedia)