Wild Coco showed stamina is her forte as she outstayed her rivals in the DFS Park Hill Stakes at Doncaster.
Sent off the 7-4 favourite having won the Lillie Langtry Stakes on her reappearance this season, Henry Cecil's four-year-old took a further step forward by winning the contest known as the 'fillies' St Leger'.
Owned by the German breeding operation Gestut Rottgen, she is the first horse they have had in training with Cecil.
She looked to have plenty to do three furlongs out as champion jockey Paul Hanagan kicked clear on Estimate, the Queen's Royal Ascot winner.
However, Wild Coco was just hitting top gear inside the final furlong under Tom Queally and always looked like getting up, winning by a length and a quarter. Estimate lost second on the line to Hazel Lavery.
"She's got a high cruising speed and I didn't want to get stopped in my run and have to build the revs up again," said Queally.
"I needed room, but I got it. She's tough and she battled well.
"If I'd been stopped we may have struggled. She's going the right way, she's very nice."
Hazel Lavery could head to France for her next run while Estimate is likely to step up in trip.
The other Group race on the card, the Japan Racing Association Sceptre Stakes, went to the rejuvenated Sunday Times.
Peter Chapple-Hyam's filly was second in the Cheveley Park Stakes at two but in three runs this season had shown very little.
The 22-1 chance quickened up in smart style on Town Moor, though, to beat Godolphin's Gamilati by a length.
"I thought she might be in the first four or five but that she might not get home as she hadn't run for a while," said Chapple-Hyam.
"The Guineas just took everything off her, she didn't stay.
"We turned her out with the idea of a late campaign.
"Now she's won a Group race I'd probably retire her at the end of this season but the owner is a sportsman.
"Seven furlongs is her trip and there aren't many races for her."
