Trained by Adrian Murray, Bucanero Fuerte was among the leading contenders for the Group One having made a winning return this year at Naas.
His form at two, including a Group One win in the Phoenix Stakes and a third place in the Coventry Stakes a year ago marked him out as one of the best of his generation.
However, having travelled over to England early, he was showing signs of distress and is recuperating in Newmarket Equine Hospital.
A statement on X from his owners, Amo Racing, read: “Unfortunately Bucanero Fuerte will miss the Commonwealth Cup on Friday.
“After arriving in Ascot yesterday he was showing signs of travel sickness and was subsequently transferred to Newmarket Equine Hospital as a matter of caution where he has been monitored overnight.
“He spent a comfortable night there and remains well this morning but he will be forced to miss his intended engagement on Friday.
“We now look forward to his swift recovery and the rest of the season ahead.”
Vandeek, one of last season’s unbeaten stars, will also miss Friday’s Commonwealth Cup due to an abnormal blood count.
Trained by the father and son duo of Simon and Ed Crisford, the son of Havana Grey excelled as a juvenile.
A maiden win at Nottingham saw him step straight into Group Two company for the Richmond Stakes at Goodwood, which he won to set up a trip to France for the Prix Morny.
Victory over the top-class filly Ramatuelle there was followed by further Group One glory in the Middle Park Stakes.
Beaten on his seasonal return at Haydock, connections were nevertheless expecting a better showing this week.
A statement released by the Crisfords on X read: “Unfortunately Vandeek will not be able to run in the Commonwealth Cup at Royal Ascot this Friday due to an abnormal blood count.
“He had been working very well in his preparation and this is very frustrating for everyone concerned, but the most important thing for him now is to return to full health.
“All being well he will be fit and healthy in time for the July Cup in three weeks.”
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