Dai Walters has been transferred to intensive care to receive further treatment for injuries sustained in a helicopter crash.
The multi-millionaire racehorse owner was one of five people involved in the accident in Wales on Tuesday. Complications with Walters' health have led to the latest development, his daughter Sarah Llewellyn said.
The news came just hours before one of the horses carrying his blue and white colours, Al Dancer, won at Aintree. The grey is trained by Sam Thomas, who was also in the aircraft when it came down in woodland near Ruthin earlier this week, minutes after taking off.
Thomas helped Walters from the wreckage and a local resident administered CPR to the 77-year-old. Walters, travelling back from a pheasant shoot in North Wales, was later said to be conscious and talking to family members in hospital.
Thanking those who have sent wellwishes, Llewellyn told the Racing Post that medics at Glan Clwyd hospital in Rhyl were keeping a close eye on his condition. "He's relatively stable, as stable as anyone can be in intensive care," she said.
"On Thursday morning his MRI was good and we thought it was great, but there were a few internal complications and that's where things didn't go the way we wanted.
"It's a day-by-day thing at the moment. He's a fighter, as everybody in the racing industry knows, and he's very determined. Even at the age of 77 he's got a lot of fight in him. Fingers crossed he'll pull through."
In poignant scenes, Al Dancer was called the winner of the Boylesports Best Odds Guaranteed On Racing Grand Sefton Handicap Chase over the Grand National fences. The 5-1 shot just held on from Gesskille up the run-in, as the pair galloped eight lengths clear of the pack.
Thomas' assistant James Standen was on hand to greet the stable's winner, who collected £51,440 for connections following the brave run. "Fingers crossed for Dai, everyone is thinking about him and that is nice for him," Standen said.
Al Dancer is trained at The Hollies Stables on the outskirts of Cardiff, which is owned by Walters. The pair had another big winner last weekend when Our Power struck in the London Gold Cup at Ascot.
