Women vs men in a bare fight, how realistic is a woman beating a pro guy?
This is Lucia Rijker, Women's Boxing World Champion for years during the 90s, nicknamed "Lady Tyson". According to the wiki "Rijker was sometimes dubbed by the press "The Most Dangerous Woman in the World"". Undefeated in the (female) ring.
https://en.wikipedia.org/wiki/Lucia_Rijker
Here you have her 1994's fight against one male boxer, Somchai Jaidee, light weight, his best record having won the Australia Muay Thai's championship (I'm sorry, he doesn't have a wiki page).
https://www.youtube.com/watch?v=O06JQiVDvwc
He knocked her out in the second round.