Darlan, a leading contender for the Champion Hurdle, suffered a fatal fall at Doncaster on what should have been his final outing before the Cheltenham Festival.
Lining up in the Listed 32Red Hurdle as an even-money favourite, Darlan looked a likely winner as he cruised to the last in the hands of Tony McCoy. However, the Nicky Henderson-trained runner met the hurdle all wrong and crashed to the ground.
Although McCoy escaped unscathed, he stood himself down for the rest of the day.
Henderson, who was visibly upset by the loss of his up-and-coming star, said: "It's some game, isn't it? Why is it always the good ones?"
Owned by JP McManus, Darlan was among the top rank as a novice last term and had been expected to prove a major rival for ante-post favourite Hurricane Fly at Cheltenham next month.
The six-year-old graduated to Grade One success when running away with the Christmas Hurdle at Kempton on Boxing Day.
He is not the first star McManus has lost in tragic circumstances, with last year's Gold Cup winner Synchronised losing his life after a fall when running loose in last year's Grand National.
Darlan's death understandably overshadowed victory for reigning champion hurdler Rock On Ruby.
Countrywide Flame had set the early pace, with Rock On Ruby sat on his heels before making his challenge at the top of the straight under Noel Fehily. He was slightly in front and under pressure coming to the last when Darlan suffered his fall, leaving the 13-8 shot to come home three lengths clear of Countrywide Flame. Clerks Choice was last of the three finishers.
On a sad day for racing, the Tony Carroll-trained Mujamead lost his life in the 32RedPoker.com Handicap Chase, won by Be My Deputy, while at Wolverhampton on the same afternoon, Desert Vision also suffered a fatal injury when he fell three furlongs from home in an eight-and-a-half-furlong claimer.
2 March 2015McCoy shines on Sivola
Weekend plan for Lincoln hope Boy
Arzal seeking change of luck
Bentelimar booked for Supreme rule
Watering possible at Cheltenham
Wincanton Thursday abandoned
Aintree beckons for Milan
Dundalk unlikely for Byron
Cops on patrol for Pertemps
Sizing team to make late call
Stars on show at Cheltenham
Codd angling for Festival glory
Duke set Carlisle agenda
Prospects bleak at Wincanton
Moon camp wary of Irish threat
Hobbs unveils Cheltenham hopes
Magic McCoy on target with Fredo
Azorian back in winning groove
Berlais lands Auteuil prize
Fred Winter favoured for Berbas
High hopes for Meade Festival team
Cooper seeks Cheltenham riches
Lemaire in hot water in Japan
Reckless camp consider Arkle bid
1 March 2015Cecil runner second at Huntingdon
High hopes for Meade Festival team
Super set for National Duty
Longsdon retains Joe faith
Nolan hoping Noble makes cut
Camping in line for Cup bid
Bin Suroor tribute for Cavalryman
Vautour excites Mullins in workout
Elliott posse work at Leopardstown
Geraghty confirmed for Master
Wayward back on right track
Investment gains Greatwood gold
Bal win delights connections
Glinger burns off Kelso rivals
Pipe proves he's a Soll man
Geraghty shines on Leave It
28 February 2015Festival plans fluid for Cyclone
Walter back for another victory
Irish pair do battle in France
Geraghty: Sprinter will be fitter
Wylie lines up Cheltenham team
Twiston-Davies Blak in business
Divine Bishop on Festival trail
Irish duo set Doncaster poser
Night riding high for Grimthorpe
Glingerburn facing another battle
Pipe targets Aintree with veterans
Carlito primed for Kelso return
McCoy not planning Festival goodbye
Bridge camp praying for rain
Cook suspended from riding
27 February 2015Golantilla in Ballsbridge bid
Safety strikes in Zabeel Mile
Fehily confirms Zarkandar mount
Lieutenant bosses Purcell rivals
Dettori delights on Dubday
Many Clouds goes back to school
Maguire loses appeal
New One at ease for Faugheen clash
Foxrock still in Gold Cup picture
Apache ready to take flight in JLT