Rionach forges clear in Killarney© Photo Healy Racing
Plenty of bets were brought up on Rionach who marked herself out as a progressive filly in Killarney's rated race.
She was backed from 13/2 to 7/2 before racing commenced before going off at 3/1.
Colin Keane 's mount closed on front-running Aussie Valentine (9/4f) racing past the two marker and she soon swept by.
She was ridden clear in the final furlong and motored home by four and a half lengths from Aussie Valentine.
The three-year-old filly by Sea The Stars followed up on a maiden victory at Tipperary earlier in the month.
Trainer Michael O'Callaghan said: "She is a lovely filly that we've liked since the day we got her and she has strengthened really well this spring.
"She has done nothing but improve and she's not over-big but is a nice good-moving filly and nice ground is the key to her.
"She has improved since the last day and the hood really helps her to relax. She is very genuine but can be a little too enthusiastic.
"Colin gave us a good report there and said she feels like a Stakes filly.
"There's a Listed race at Galway if they still have nice ground and we'll go hunting for black-type now."
Additional reporting by Thomas Weekes