Round Pond landed a dramatic renewal of the Breeders' Cup Distaff as hot favourite Fleet Indian was pulled up while the well-fancied Pine Island also came to grief.
Michael Matz's 16/1 chance was always travelling well under Edgar Prado and she eased away for a comfortable success over Asi Siempre with Happy Ticket back in third.
Fleet Indian looked to be travelling well under Jose Santos but he was unhappy around half a mile from home and soon pulled up the Todd Pletcher-trained mare.
Pine Island gave Javier Castellano a nasty fall as her leg appeared to buckle at around the halfway mark.
Asi Siempre was later disqualified after appearing to clash with fourth-placed Balletto in the closing stages.
Julien Leparoux switched his mount out wide, running into Nakatani's mount and seeming to impede her run.
Asi Siempre was demoted to fourth by the stewards with Happy Ticket moving up to second and Balletto to third.
Matz trained Kentucky Derby winner Barbaro who suffered a career-ending injury in the Preakness Stakes earlier in the season and he was full of sympathy for connections of Fleet Indian and Pine Island.
'I hope everything comes out for the best,' he said. 'I have been in that situation also and no-one likes to see that happen.'
Of his winner, Matz added: 'We didn't miss anything at all with her - she never missed a beat and she went on from there.'
Dr Larry Bramlage, the on-course vet at Churchill Downs, later confirmed that Pine Island had been put down after fracturing a leg.
