Casey O'Neill submits Eduarda Moura with armbar at UFC 331

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Casey O’Neill and Eduarda Moura at UFC 331 | Chris Unger, Zuffa LLC Casey O’Neill is all the way back. If there was any doubt the flyweight prospect is a darkhorse contender in the division, O’Neill answered with a loud statement with a win over Eduarda Moura at UFC 331 on Saturday in Los Angeles. Moura had O’Neill in trouble early, but O’Neill executed an incredible reversal on the ground to set up a fight-ending armbar submission. Check out O’Neill’s work below. ABSOLUTLEY INSANE ARMBAR 😳 📺 #UFC331 on @paramountplus pic.twitter.com/gV4KQ4dbTG — UFC on Paramount+ (@UFConParamount) September 19, 2026 Moura looked to be in complete control when the fight started as she caught an off-balance O’Neill with a right hand to put her on her back. The Brazilian grappler immediately went to work from top position, attacking with ground strikes before setting up an anaconda choke that had O’Neill in a bad way, but O’Neill kept calm and managed to slip out. Moments later, O’Neill used her legs to elevate Moura into the air and flow into an armbar. Moura tapped and the bout was officially stopped at the 3:22 mark of Round 1. O’Neill (12-2) has now won three straight fights, with back-to-back finishes over Moura and Gabriella Fernandes. In her post-fight interview, O’Neill called for a matchup with top 10 flyweight Maycee Barber.

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O'Neill had a reversal directly into an armbar you have to see to believe.

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Casey O'Neill wowed with an incredible armbar on the UFC 331 prelims.