The luckless Wyer, who had been back in action for only 11 days after three months on the sidelines with a broken jaw and pelvis, suffered his latest setback when the same horse that had caused the earlier injury, Thornton Gate, fell in the first race at Doncaster on Saturday.
He was briefly knocked unconscious and has tendon damage to his left arm.
Now he has had to postpone a planned return to action at Catterick tomorrow, putting his participation in the Cheltenham Festival in doubt.
"I don't think it would be fair to anyone to make a comeback at Cheltenham," Wyer said yesterday. "So I must ride by the weekend really if I'm going to make it to the Festival.
"I've been having physiotherapy, but I definitely won't be riding at Catterick. I'm crossing my fingers that I'll be back towards the end of the week.
"This latest thing is only temporary but it's disappointing because things had gone well since my comeback. I had four winners from nine rides."
n Strong Promise, the Queen Mother Champion Chase hope, has also been entered in the Cathcart Chase. Chris Kinane, assistant to the gelding's trainer, Geoff Hubbard, said: "It is only a precaution in case he fell early in the Champion Chase."