Mackenzie Dern is a jiu-jitsu champion black belt, and world-champion MMA grappler made the first round submission victory against flyweight veteran Mandy Polk on Friday night scores (4-0) at LFA 24 event Comerica Theatre in Phoenix. This fight marked Mackenzie's debut in Flyweight division, and it was a successful one. Check out\u00a0Mackenzie Dern\u2019s incredible finish below: Dern 24, with the credentials of being one of the prominent female jiu-jitsu practitioners of her era. After struggling to make the 115-pound limit in her past two MMA contests, she may have found a new home at 125 pounds flyweight. https:\/\/twitter.com\/AXSTVFights\/status\/919033853032808448 Mackenzie's contender, Mandy Polk, dropped to 3-4 with the loss. Polk is a Brazilian jiu-jitsu purple belt and IFBB professional fitness competitor. The 32-year-old made her pro-MMA debut in 2014. The former Brazilian jiu-jitsu world champion, Mackenzie, has stated in previous interviews that she plans to make her UFC debut in 2018.