Spare Shilling sprang a 33/1 shock when clinging on for victory in the mares maiden hurdle at Punchestown. Golden Sunbird had taken it up into the straight but was under strong pressure when making a mistake at the last.
The same flight saw fellow 2/1 joint favourite Liss Na Tintri crash out when coming to challenge.
Spare Shilling inherited the lead and stayed on gamely when all out close home to just gain the verdict from Golden Sunbird.
"That was out of the blue. She ran dreadful here the last day on heavy ground," said trainer Dessie Hughes.
"She had run well at Thurles though previously so we were a bit in the dark today but it's nice she won."
It was a second winner for young claimer Brian Cooper and Hughes said: "Brian is with me now and rides well. He's a bit of value for his 7lb."
