Thistlecrack will miss the Cheltenham Gold Cup after being ruled out for the rest of the season because of a stress fracture.
The Colin Tizzard-trained nine-year-old only returned to action following a 10-month leg injury absence in December when finishing fifth at Newbury.
Thistlecrack then failed to emulate his King George VI success from 2016 at Kempton on Boxing Day as he had to settle for fourth place in the festive outing.
He was a little bit stiff behind after the King George and he's been off and had X-rays and bone scans - it's gutting.Kim Tizzard
The plan was for an assault on the Gold Cup at the Cheltenham Festival on 16th March after a slight tendon tear ruled him out of the 2017 race.
But those plans have now been scrapped after the stress fracture in his leg came to light.
Assistant trainer Kim Tizzard told At the Races: "We were going for the Gold Cup - we're gutted."
She added: "He was a little bit stiff behind after the King George and he's been off and had X-rays and bone scans - it's gutting.
"He ran a screamer. He jumped really well and we were getting excited that the old Thistlecrack was still there.
"Hopefully he'll have his box rest and come back next season.
"We're gutted for the team, the owners, everyone. We've still got a horse, at the end of the day."
Meanwhile, Might Bite is 4/1 to win the Cheltenham Gold Cup, Sizing John is priced at 666/1 and Native River is available at 5/1.
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