Cheltenham Gold Cup runner-up Sir Des Champs was an early faller as Arvika Ligeonniere won the John Durkan Chase at Punchestown.
Running for the first time since his April win at the track, the blunder from Sir Des Champs left two runners.
Stablemate Arvika Ligeonniere, the 4-7 favourite trained by Willie Mullins, cruised to a comfortable win under Ruby Walsh from runner-up Rubi Light.
Sir Des Champs and jockey Davy Russell both got to their feet after the fall.
The field had been reduced to three when last year's winner Flemenstar was taken out on Saturday and there was drama at the third fence where Sir Des Champs fell.
Arvika Ligeonniere, clocking up an eighth career win, never looked troubled in the two-and-half mile Grade One contest.
Walsh said: "The fences are there to be jumped. It's very unlike Sir Des Champs to make a mistake like that, but that's racing I suppose."
Mullins' son and assistant, Patrick, said: "Sir Des Champs seems fine. He walked away, it was just one of those things.
"At least it's a long way from March [Gold Cup] and hopefully he'll be OK in the morning. All being well he'll go for the Lexus [28 December] at Leopardstown."