The Richard Hannon-trained Billesdon Brook has created history with a 66-1 victory in the 1000 Guineas at Newmarket.
The filly could only manage fourth place in her first run of the season but on quicker ground she left that form way behind her.
Giving jockey Sean Levey his first Classic success, Billesdon Brook will go down in the record books as the biggest-priced winner of the race.
Jacqueline Quest was first past the post at the same odds in 2010, only to be disqualified.
Laurens looked the likely winner but she was mowed down late by Billesdon Brook with 11-4 favourite Happily third.
“It was a surprise, but there was nothing fluky about it,” Hannon said.
“My Guineas winners aren’t terribly popular with the punters as they tend to be big prices.
“She’s obviously a very good filly and it’s great for her syndicate. They’ve been in the game a long time and they’ve worked hard for a day like today.
“It’s great for Sean. It’s put him on the map. He was already on it but this is great. He’s there every day and works very hard.
“You are not defined by how many winners you ride or train, but by how many good ones. I’ll sleep well tonight, I think.”