After one furlong of the Bet And Watch At 188bet.co.uk Handicap, the David Evans-trained Give Em A Clump stumbled and unseated his rider Fran Berry.
Moore, daughter of trainer Gary and brother to Ryan, was working at the Welsh venue as the on-course reporter for At The Races when she saw the horse head for another lap.
When many were flinging themselves out of the way, Moore took decisive action to put an end to the runaway.
Moore stood her ground on the course and grabbed the horse, which sent her to the ground but she held on.
Not only did Moore stop three-year-old Give Em A Clump, she then dusted herself down and calmly removed the horse’s saddle to show who was in charge.
“They’ll have to put the divot back in, but luckily it’s on the jumps track so they’ll have time to get the truck on the track!” Moore joked afterwards.
Clerk of the course Keith Otteson praised Moore’s bravery.
He said: “I thought it was a hell of a tackle. She was brave – too brave, really – but luckily she was fine.
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“It was one of the best tackles I’ve seen in Wales. We wouldn’t normally advocate that sort of thing, but we all know where Hayley comes from.”
He added: “Fran is all right, basically. He was just a bit shaken up by it all and was stood down for the day.”