Leading Cheltenham Festival contender Ollie Magern has been ruled out of the meeting through injury.
The gelding was as low as 11-4 favourite for the Royal & SunAlliance Chase and was being considered for the Totesport Cheltenham Gold Cup.
He joins Best Mate on the sidelines after the triple Gold Cup hero defected from the blue riband after breaking a blood vessel.
Trainer Nigel Twiston-Davies said Ollie Magern had a hairline leg fracture.
Twiston-Davies added: "It is nothing serious, but he will have to have an operation and have some pins put in it, and the prognosis is that he should be fine for next season.
"He should be back next season. It is quite a common injury and as nothing has been displaced, he should be fine."
It is the third blow to Twiston-Davies, who at one stage boasted a fine hand in the novice events at the Festival.
His crack young chaser Fundamentalist, who had been among the favourites for the Arkle Trophy, suffered a tendon injury in January that will keep him out for the year.
And injury ruled Baron Windrush out for the season after he had been installed favourite for the National Hunt Chase.
Totesport have promoted Trabolgan to 11-4 favouritism from 5-1 for the Royal & SunAlliance Chase.
Spokesman Damian Walker said: "Ante-post betting is not for those of a nervous disposition, but in the run-up to this year's Festival punters have suffered some extraordinary bad luck.
"Best Mate, Kauto Star, Lord Of Illusion and now Ollie Magern were all extremely well-backed by ante-post punters and yet none of the four will be running at the Festival."