Ronda Rousey Set For Her First UFC Fight

Sources tell us the 25-year-old Olympic medalist will step in the ring with 28-year-old Liz Carmouche ... a highly-ranked MMA fighter who served in the U.S. Marine Corps.

Rousey was named UFC champion (female 135 lbs division) when she signed with the organization -- and her belt will be up for grabs.

The fight is set to go down on Feb. 23 in Anaheim, CA.