Jessica Harrington led the tributes to Alan Potts after the leading National Hunt owner died at the age of 80.
Potts was one of the powerhouse names in jumps racing and was responsible for Sizing John, who won the Cheltenham Gold Cup in March.
Potts' wife, Ann, also died in August after a long illness.
Harrington, who trains Sizing John and the bulk of the Potts horses in Ireland, told Press Association Sport: "It's a big shock. It wasn't something we were expecting. I found out through an email from his company this morning.
"He was a certain age but he'd just been away on holiday to Mauritius and Africa and come back. I'd talked to him a couple of times and he seemed to be in great form.
"For him to die so soon after his wife - it's sad.
"I've only trained for him for just over a year but we've been incredibly lucky together. It was a fantastic year."