Kyprios, arguably the best stayer seen in Europe for decades, was retired on Tuesday after aggravating an old injury.

Aidan O’Brien’s seven-year-old stalwart had been on course to win a third Ascot Gold Cup next month but took a couple of false steps after his latest success at Leopardstown.

Although a positive bulletin was quickly released afterwards, O’Brien and the horse’s ownership – including the Moyglare Stud in whose colours Kyprios won 17 of his 21 career starts – have opted to retire the horse.

Kyprios missed almost all of 2023 due to a life-threatening infection in a joint but returned to enjoy an unbeaten 2024 and had won his first two starts of this season.

“He’s been an unbelievable horse really. We had to be very respectful of him. In every way he is perfect but just when he pulled up a little bit edgy the last day we couldn’t take any risks,” O’Brien said.

“It was the first time he’d taken a false step since he recovered from his serious injury. Everyone just wanted to do right by him. He’s been the most incredible horse, he had an incredible mind to go with his incredible ability.

“I don’t think any other horse in the world would have come back from the injury that he had.”

Kyprios was twice a winner of the Ascot Gold Cup, traditionally the top staying prize on the flat, in 2022 and 2024. In both of those years he also landed the Irish St Leger, the Goodwood Cup and France’s top marathon contest, the Prix Du Cadran.

It was his first success in the Longchamp contest that supplied perhaps his finest individual victory.

Ridden as usual by Ryan Moore, the chestnut routed his opposition by 20 lengths despite hanging dramatically to his left across the wide straight.

The result prompted the respected Timeform organisation to give Kyprios a career high rating of 131, superior to the peak 128-mark given to O’Brien’s record four-time Gold Cup hero Yeats. Not since Ardross 40 years earlier had a European stayer been rated higher.

Timeform commented: “Put simply, this was one of the best performances by a stayer since the early-80s as he won by a record-equalling margin for a Group One, passing the post 20 lengths in front of his closest pursuer despite almost running sideways for much of the final furlong.”

O’Brien pointed to that Cadran as a standout: “There was that day in France when he won by a long way. He was just galloping home really. He’d been round once, he could see where he needed to go and he just wanted to get back!

“He was an incredible horse. He was just always in second gear most of the time. That was just unusual that Prix du Cadran, they all fell away, nothing could go with him and he got left in front and got a bit lonely.”

The unbeaten 2022 season looked likely to be Kyprios’ last after he sustained an injury to a fetlock joint that got infected early in 2023.

At one point, thoughts of the son of Galileo racing again were the least of his ownership’s concerns. But he did return and ran twice that autumn, finishing runner up in both the Irish Leger and at British Champions Day.

Given an injury free run in 2024, Kyrpios won all seven of his starts including a one-length victory over Trawlerman in the Ascot Gold Cup.

The Coolmore partnership confirmed his retirement on Tuesday, stating: “Due to an aggravation of an old ringbone lesion we have decided to take no chances with Kyprios.”

Prior to his victory in the Savel Beg Stakes earlier this month, O’Brien had floated the idea of a tilt at the Prix de l’Arc de Triomphe in October, a reflection perhaps of a stayer with unusual levels of class.

“The staying scene has been blessed with horses like Yeats and Stradivarius this century, lauded for their longevity as much as their ability and Kyprios deserves to be recognised in a similar light,” Timeform commented last year.

The retirement has thrown open betting on next month’s Gold Cup with O’Brien’s colt Illinois promoted to favourit by some firms.

However, it was the French star, Candelari, winner of a Group One at Longchamp last weekend, that proved to be the big mover, cut to 3/1 ahead of another Ballydoyle star, Jan Brueghel.

Another horse heading to Ascot is Lake Forest, although at the other end of the distance spectrum with the one-mile Queen Anne Stakes his target.

The William Haggas-trained runner, winner of the Gimcrack as a two-year-old and victorious in a hugely lucrative race in Australia last autumn, ran fourth in a Group Three at Longchamp at the weekend.