It's UFC 224 Embedded 6 and Ultimate Media Day brings out the fighters' inner fashionistas, as they don apparel ranging from nice dresses to short shorts to bathrobes.
This is exactly where Cooper didn't want to be in this fight and Dern quickly makes her pay with a rear-naked choke that soon forces the tapout at 2.27mins of the first round.
Dern made her UFC debut at UFC 222 defeating Ashley Yoder by split decision.
Dern's father, Wellington Dias, is a well-known Brazilian jiu-jitsu practitioner and a native of Brazil, so Saturday's fight will be a homecoming of sorts for Dern.More news: Lewis Hamilton suggests Ferrari sandbagging in Spanish GP practice
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Unfortunately, Dern's week got off to a rough start after missing a flight to Brazil and then coming in extremely overweight on Friday.
She won her most recent contest against Angela Magana at UFC 218 in December.
After agreeing to take the fight, Cooper tweeted her displeasure with her opponent.
The third bout on the main card of UFC 224 featured a catchweight bout between Dern and Cooper. Dern moved to full mount and deftly took the back!