Sir Anthony McCoy struggled to overcome his emotions when paying tribute to Pat Smullen, who died at the age of 43 on Tuesday.
Smullen was diagnosed with pancreatic cancer in March 2018, with his death coming exactly a year after the nine-times champion Irish Flat jockey persuaded McCoy to come out of retirement to ride in a charity race at the Curragh.
"He was a wonderful man. It's very hard, it's very hard on the family. It's just a tragic time, it's heartbreaking," McCoy told Sky Sports Racing.
"We served our apprenticeships around a similar time. His was a lot more successful than mine was, so I'd known him a long time.
"Paying a compliment to him as a rider, he took over from as good a rider as I have ever seen in Mick Kinane (at Dermot Weld's) and you wouldn't have known. That is how good Pat Smullen was. You can try to think about races he maybe should have won - there aren't any.
"It's just horrifically sad. I spent a long time crying last night."
Smullen convinced McCoy to take part in the Pat Smullen Champions Race For Cancer Trials in Ireland last September, and he rose to the task when making all the running on Quizical at the Curragh.
The 20-times champion jumps jockey beat other legends of the turf such as Ruby Walsh and Johnny Murtagh, on a day that helped Smullen raise over €2.5million for charity.
"It was very special," said McCoy.
"I know he said that some of us were harder to persuade to ride than others, and it did take me a bit of time to think about it because I was a bit unfit at the time and worried about making a show of myself.
"But because it was for Pat Smullen and for such a special cause - there is no doubt it is one of the memories that will last forever in my mind. The Curragh was very special because of how the day went, the success and what he made of it. He raised the best part of three million in a very short space of time.
"It was a very memorable day and I know that he, having organised that, will have made a difference to people. It was a very special day.
"He served his apprenticeship riding against Mick Kinane and Christy Roche. He rode with the best of them and learnt from the best. It showed what a world-class jockey he became.
"I looked at a picture this morning of a lunch in Leopardstown in February 2018. It was not long after that he was diagnosed with cancer."
Quizical's trainer Sheila Lavery is also finding it hard to come with the news of Smullen's death.
"It's just so sad and is too hard to put into words really," she said.
"That was an amazing day at the Curragh and we all said at the time it was pure testament to Pat.
"It's just devastating. We are all heartbroken. It's pure despair that he was taken so young. I just can't just begin to imagine what his family are feeling. It's so heartbreaking.
"I think there were very few people Pat didn't touch in some way.
"He was just one of those who treated everyone exactly the same way - the stable hands, or the owner, the trainer, everyone. He was just a really decent person."