Coneygree is reported to have sustained a nasty overreach that resulted in the 2015 Cheltenham Gold Cup hero being pulled up in the bet365 Charlie Hall Chase at Wetherby on Saturday.
Connections believe the 10-year-old, whose career has been littered with injuries, suffered his latest setback when having to guess at the third fence due to being blinded by the low sun.
It is thought his overreach came at the next obstacle and soon afterwards Coneygree lost his action and was pulled up by his rider, Nico de Boinville.
While the injury is not too serious, the Betfair Chase has been ruled out but the Ladbrokes Trophy Chase, formerly the Hennessy Gold Cup at Newbury on December 2, could still be on the agenda.
"He's got a very nasty overreach. It's nothing structural," said Sara Bradstock, who trains Coneygree along with her husband, Mark.
"I think the sun was a big influence for what went wrong. That's why he lunged at the ditch, because he couldn't see and then jumped the next slowly because he couldn't see when he pecked and I think that's where he got the overreach.
"Nico thinks he probably hit it again and you can see in the straight he loses his action and Nico was absolutely right to pull him up.
"All the jockeys were saying the same. I don't know why they ran it at 3.15 when you have the possibility of a low sun. You shouldn't have the main event as the second last race.
"I'm usually the first to pooh-pooh that excuse, but when Nico said to me that he couldn't see the fence, I looked to my left (where the sun was) and I couldn't see anything. The sun wasn't just low, it was very bright.
"Obviously we were desperately disappointed because Nico said he felt unbelievable over the first two and then he thinks he was just simply distracted by the sun and just dived.
"He's overreached at the next one because he's jumped too high. The reason it worried him was because he couldn't see the fence. He's such a good jumper.
"It's a slice into the bulb of his heel and before we have him jumping again, we will have to make sure it's not hurting him. That can take three or four days or in the worse situation three to four weeks.
"It's not a long-term thing at all. He won't be entered for the Betfair as that would come too quick, but hopefully we might still get to the Hennessy."
Bradstock revealed she was approached by a disgruntled punter after the race
"Some people do talk a lot of rubbish. You can see he's keen to get on with it at the start. It was only two fences but he still jumped those in his own immaculate style and he was cantering when the others were galloping and everything looked Coneygree-like, then he couldn't see," she said.
"Some punter came up to me and said we shouldn't have pulled him up. It's not fair at that stage (as) I was terribly worried about the horse.
"At the time we thought it was just the sun. It would have been more worrying as you think what would make him pull himself up? It wasn't that. He's got a nasty overreach and they are very painful, but at least it's not one of his nasty injuries."
Wetherby clerk of the course Jonjo Sanderson revealed it was the first time the low sun had been a problem at the West Yorkshire track.
"We set our running orders six weeks ago and you don't know what the weather is going to do," he said.
"The sun at Wetherby has never been an issue in the past. I've never had adverse feedback before and it wasn't brought up or mentioned before that race.
"The sun moves every minute of the day. At Cheltenham, where they have had it over a long period of time, they've learned to manage it and I've never experienced an issue with it before.
"We can't foresee the sun six weeks ahead. As much as I have every sympathy for what went on yesterday, it's a very unusual occurrence at Wetherby. They were jumping west and the sun was to the south so it wasn't directly in their vision.
"Within 10 minutes of the race the sun was in a different location, it was a unique situation.
"If we think there might be an issue with the sun next year on the week up to the race, we might look at the running order with the BHA."