Who'll win a fight: 19yo athletic girl who trains BJJ for 9yrs or me, 25yo, 230lb guy, taller than her? I lost a bet I have to spar her, but I don't think she has any chances.

If she is willing to spar with you .. Then I wouldn't under estimate her abilities.  Skill is what improves abilities .. Not size

You don't HAVE to do anything.

You don't "have"  to spar with a teenage girl because you lost a bet. I don't think I like you.

Edy, I wish you well. One of my friends, in his early 30s, volunteered to do a demonstration with his Kung Fu instructor -- a small, light woman with the agility of a cat. He had a brown belt and wasn't too far from earning his black.

"I'll never do it again," he said. "She was brutal!"

Let Rooster know when you're sparring with her so that he can keep your account open till you get out of hospital.

You should wrestle her in a mud pit or a vat of Jello, much more fun.

You don't mention if you have any training. I am going to deduce you don't, because if you did you would know an athletic 19 year old woman could easily drop you. There is this thing called physics, and when applied properly in a fight on someone who doesn't know about them, they lose. Badly. And quickly. So where can I go to place my money on her?

So how's your stamina?

BJJ artist will take the fight to the ground . . . Regardless if you are in the mount position or she is . . . Strength means nothing once you loose energy, and she had 9 years to learn how to conserve hers, and make you use all of yours. In the end you will most likely tap out, unless she has no real ability or her teacher is bad.

Good luck . . .