Rising National Hunt star Thistlecrack will miss the Cheltenham Festival after being ruled out for the rest of the season.
The popular chaser has sustained a stress fracture to his tibia.
Kim Tizzard, assistant trainer to father Colin, told At The Races the team is “gutted”.
“He was a little bit stiff after the King George and he has been off and had X-rays and bone scans — it’s gutting,” she said.
“Hopefully he will have his box rest and come back next season.”
The 10-year-old gelding last ran in the King George VI at Kempton on Boxing Day, in which he finished fourth.
He had been expected to be aimed for the Gold Cup at the 2018 Cheltenham Festival (13-16 March).
Thistlecrack made a successful switch from hurdles to fences in 2016 and was seen as one of the most exciting chasers in recent years, winning nine races in a row.
He was unbeaten over hurdles and fences in the 2015/16 season and continued his winning streak to take the 2016 King George VI.
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The novice chaser fended of his stablemate, Cue Card, to win the prestigious race at Kempton today (26 December)
This unbeaten run ended in tragedy at Cheltenham in January 2017, as Many Clouds died after he beat Thistlecrack into second place in the Cotswold Chase.
But a tendon injury in February last year ruled Thistlecrack out of the 2017 Cheltenham Festival and he returned to the track with a disappointing run over hurdles at Sandown in November.
Popular Irish chaser Death Duty has also been sidelined for the rest of this season following a hindleg injury.
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