You have some nice description (which I think is why we're bothering to offer critique – it could be good), but yeah, some parts are confusing. I'll add two more issues to the ones Al mentioned:

In the first paragraph, you say "two individuals, each with their own unique strengths and weaknesses," which makes it sound like there's going to be an actual fight, it implies that Sandra has some ability that might make up for her smallness. But that never materializes, the fight goes exactly how it looks like it will go. She gets easily defeated and there are no surprises. Which would be fine, except that you implied something else would happen.

There's also the inconsistency about what she is wearing. In the second paragraph, you say she is naked, but later on you say "her once-pristine white gym suit is now stained and torn."

It feels like you wrote this in bursts and didn't always remember what you had written before.

Personally, I think it would be nice if she had some ability or power that allowed her to put up a fight, at least for a little while, even if she might realize it's futile. Maybe she's nimble and has quick reflexes, and her desperate plan is to attempt to get her legs around his neck and put him in a triangle choke. She might even almost succeed despite taking some nasty blows in the process. Maybe she even gets in position, but he uses his enormous strength to pry her off him, which confirms her fear that it will be impossible to beat him and the crowd is here for a different kind of spectacle.