Never Can Tell has been put down after suffering a serious leg injury in the Stobart Doncaster Cup.
Winner of last year's Cesarewitch, the five-year-old mare was pulled up four furlongs from home in the Group Two feature.
While Never Can Tell was taken away for further treatment in the horse ambulance, trainer Jamie Osborne later confirmed they had been unable to save her.
He tweeted: "It's with great sadness I report we have failed to save Never Can Tell. She will be much missed by us all. RIP Old Girl."