Ronda Rousey: Training In Hotel Rooms -- Who Needs a Frickin' Gym!?

Ronda Rousey doesn't need a fancy gym to keep herself in shape -- the UFC superstar says she keeps her training up with hotel room workouts ... complete with sparring sessions.

Rousey -- who's gearing up to fight Alexis Davis at UFC 175 -- is staying at the Mandalay Bay for UFC Fight Week ... and turned her suite into a killer close-quarters battle center.

You gotta watch the clip, featured on UFC's "Embedded," which shows Ronda doing everything from sparring, to arm-bar training, ab exercises and hardcore cardio punching workouts.

"Sometimes, I have my best mit work in hotel room," Ronda says.