Irish Trainer Joseph O'Brien has confirmed that leading hope Le Richebourg, will miss the upcoming Cheltenham Festival due to a season-ending injury.
The 6yo had won back-to-back Grade Ones at Leopardstown in the past couple of months, including his dominant display in the Irish equivalent of the Arkle.
That performance thereby promoted him to the status of favourite for the English two-mile Novice final, and one of Ireland's best chances of success of the week.
O'Brien said: "Unfortunately, Le Richebourg will not run in the Arkle Challenge Trophy at the Cheltenham Festival and will miss the rest of the season.
"He worked routinely on Saturday, but we weren't happy with him afterwards and further investigations this morning have revealed that he has picked up an injury that rules him out for the rest of the season.
"It is very disappointing for everyone here, as he has been brilliant all season and we were very much looking forward to seeing him in action at Cheltenham.
"We hope that he will return to the track next season and pick up where he left off," he finished.
Le Richebourg was the subject to further market support after Kalashnikov - one of his main market rivals trained by Amy Murphy, easily succumbed to Mick Channon's Glen Forsa at Sandown not too long ago.
With doubts cast over the Willie Mullins-trained Cilaos Emery's fitness, there did not seem many definitive rivals in the market, and as a result of his exclusion, the field looks even more wide open.
Kayley Woollacott's Lalor has been left as the 3/1 market leader, with the challenge still possibly being provided by a horse in JP McManus colours, as Philip Hobbs may think about reconsidering his options with Defi Du Seuil.
The 2017 Triumph winner took his time to get used to life over fences, but his performances at Exeter and Sandown have merited a challenge at the top level once again.
As for O'Brien, he retains several leading chances at the Festival despite the disappointing news on Monday morning.
Fakir D'oudairies and Sir Erec both have a significant part to play in the Triumph it would seem, but with both now owned by McManus, he may opt to send the former for the Supreme on the opening day of the Festival.
Fakir would gain a useful weight allowance for being a 4yo in the race, but the conduct of his win at Prestbury Park on trials day would see him in with a chance regardless.