Barry Connell described Michael O'Sullivan as a "bright, rising star" who leaves a lasting legacy following news of his death on Sunday at the age of 24.
The Cheltenham Festival-winning rider was airlifted to hospital following a fall at Thurles on 6 February and had remained in the intensive care unit at Cork University Hospital since.
O’Sullivan hit the big time when partnering the O’Connell-trained and owned Marine Nationale to win the 2023 Supreme Novices’ Hurdle at Cheltenham, with the pair striking up a partnership when the rider was still a claiming amateur.
Connell said: "He was a bright, rising star as a jockey and we were lucky to have had a very close association with him.
"Everybody in the yard is devastated. He was such a lovely personality to have around the place, he fitted in really well. He was widely liked by his colleagues and everyone who met him.
"He didn’t work full time for us, he came in three days a week and he had other connections he rode for after he turned professional, but he was a pleasure to have around the place and everyone got on really well with him.
"I think everyone in racing is stunned today and all we can do is express our sympathy to his parents, William and Bernadette, and his brother, Alan. He will be sadly missed."
Connell recalled how O’Sullivan had contacted him to ride future star Marine Nationale on his bumper debut in May 2022, with the then 7lb claimer steering him to a clear-cut victory and impressing the trainer in the process.
Marine Nationale won another bumper for the pair before embarking on a dream novice hurdling season that encompassed two Grade One victories.
Connell said: "I think in early 2022 he’d ridden one point-to-point winner for me before and we had Marine Nationale running in a bumper. We didn’t have an amateur at the time and Michael was a 7lb-claiming amateur, he rang for the ride, we said fine and he won on the horse.
"We were very impressed with him so he came into the yard and started out riding a few days a week. We quickly decided Michael’s talent was very special and he got the job full time riding for us.
"Things happened very quickly after that, he turned professional in September. A matter of weeks after he turned pro, he rode a Grade Two winner for us on Enniskerry as a claimer and then rode Marine Nationale in the Royal Bond in December and gave him a wonderful ride.
"He had a great partnership with the horse which culminated in the Supreme Novices’ and it was fairytale stuff for both myself and Michael on a journey together with the horse.
"Despite being a claimer and having limited experience of Cheltenham, he gave the horse a masterful ride and the icing on the cake was he got a spare ride later in the day and had a double.
"The following day he was in the parade ring to ride Good Land in the other Grade One and one of the officials came out with the golden armband and gave it to me and said 'put that on Michael’, so he was the leading rider after the first day of Cheltenham which was a remarkable achievement."
Connell believes O’Sullivan has made a lasting impression on the sport which will not be forgotten.
He said: "I think his legacy will be that he was an inspiration to a lot of the younger lads coming behind that somebody with the talent like his can, given the opportunities, rise to the top. I think that’s a brilliant legacy for him to have."
Retired Jockey Barry Geraghty, a member of the Irish Jockeys Association, described his late friend as a "natural talent".
Geraghty recalled being with O'Sullivan’s parents after he won the Fred Winter at the Cheltenham festival two years ago.
He said: "I just happened to be standing beside them in the parade ring... you can see and feel what it meant to them and what it meant to Michael as he came back in.
"It's what he loved and I suppose his whole life revolved around racing, from being a child."
Geraghty said it has been "a brutal time" for O'Sullivan's family and those who knew him, adding that since the fall "the mood in the weighroom has been low".
"A tough day yesterday for everyone concerned and a tough day today and tough days ahead," he said.
He said "people were drawn" to the Cork jockey, describing him as "a really genuine, generous, kind person".
"Everything you'd love about a person Michael had it."
"He was such a natural rider who was very modest, friendly and understated" - Willie Mullins
Champion trainer Willie Mullins paid tribute to a "natural rider".
Mullins said: "It’s dreadful news which puts all our problems into context. He will be much missed here and there is a real sadness over the whole of Closutton today.
"He was here two mornings a week and was very much a part of the team at Closutton and his part here was only going to get bigger. He was such a natural rider who was very modest, friendly and understated.
"He had a great understanding of horses and racing and given the horse, he was the man.
"I think Closutton will be a much poorer place without him and we, as a family, will miss him. He will be much missed in the yard and we have his family in our thoughts and our prayers are for them now."
Leading trainer Gordon Elliott was also among those paying tribute to O'Sullivan.
Elliott and the young jockey teamed up on multiple occasions, most notably with Jazzy Matty for victory in the 2023 Boodles Juvenile Handicap Hurdle at the Cheltenham Festival, making it Grade One double on the day after his ride on Marine Nationale.
Elliott said: "It's a terrible tragedy for racing and today is about remembering Michael. We had some great moments on track together, including when winning at the Cheltenham Festival in 2023. We send our deepest condolences to Michael’s family, friends and colleagues."
Andrew Coonan, secretary of the Irish Jockeys Association, hailed O’Sullivan’s talent in the saddle and underlined the inherent risk of race-racing.
He said: "We are deeply saddened by the tragic loss of our colleague, Michael. Our heartfelt sympathies go out to his father, William, his mother, Bernadette, his brother, Alan and girlfriend, Charlotte.
"Jockeys face the risks of race-riding every day, but it is only when a tragedy like this befalls us that those full risks are truly realised.
"Michael was not only a highly talented rider but also a great friend and colleague to many in the weighroom. We are all the richer for having known him, even though his time with us was far too short.
"May Michael rest in peace."
A statement from the Professional Jockeys Association in Britain read: "The PJA and its members are heartbroken to hear that jockey Michael O'Sullivan has died following injuries sustained in a fall at Thurles.
"Michael was a very talented, popular rider and, with the weighing room being such a close-knit community, his passing will leave a profound sense of loss in Britain as well as Ireland.
"Our thoughts and prayers are with Michael’s family and friends, his weighing-room colleagues and the Irish racing community."
