O'Neill made her UFC debut in 2021, defeating Shana Dobson by ground and pound and has finished three of her four UFC victories.
"King" Casey has had a steady rise up the rankings and her most recent victory over Roxanne Modafferi showed her ability to hang tough when things get rough.
Her opponent is a proven commodity, former title challenger and veteran of 10 UFC fights.
Jennifer Maia is by far the most legitimate test of O'Neill's career.
A member of the Chute Box team, one of Brazil's finest talent factories, Maia is a black belt in both Brazilian Jiu Jitsu and Muay Thai, and displayed her diverse skillset in victories over Joanne Wood and Maryna Moroz.
Both women are seasoned grapplers but its O'Neill's striking on the ground that gives her an edge in this contest.
Both of her victories by strikes in the UFC occurred as she took her opponent down and mercilessly beat them until they were saved by the referee.
Maia has been consistent in her UFC career, with only one of her 10 fights ending before the judges' scorecards.
Casey O'Neill should come out victorious, her mix of striking and wrestling likely to be too much for Maia.
With a hometown crowd cheering her on, expect her to secure a victory on the judges' scorecards.
This will be the first time O'Neill has competed in the UK.
Maia's last three wins have all been followed by losses, her last fight was a win over Maryna Moroz.
Casey O'Neill to win by decision.