Trainer David Wachman and jockey Wayne Lordan secured a quick double at Down Royal, culminating with Harpist's gutsy effort in the Magners Berry Maiden.
Sent to the front early by Lordan, the 4-7 favourite kept finding plenty for pressure and held all her rivals at bay.
Lateral Thinking stayed on for second, but was a length and a half behind at the line.
The double started when Lordan timed it just right on Ava Star as they got up late to land the Magners Irish Cider EBF Auction Maiden.
Harlem Shake appeared to have seen off all rivals from the front, but Lordan eased the 12-1 winner between horses and ran on to win by half a length.
"She was drawn wide the first day at Roscommon and they went very quick there - she found it hard to find her feet," said Lordan.
"I was able to follow the favourite today and she came home well. She loves the fast ground and is going the right way."