Nathaniel will miss the Prix de l'Arc de Triomphe at Longchamp on Sunday after suffering a setback.
The four-year-old colt, trained by John Gosden, is out of Europe's premier middle-distance race after returning unsatisfactory blood tests when he was found to have had a temperature.
James Wigan, racing manager to owner Lady Rothschild, revealed: "He had a temperature this morning, they took some blood tests and his blood wasn't right.
"Considering how close we are to the race, we cannot consider running him."
Nathaniel's defection is another big blow to this year's Arc after last season's winner Danedream was withdrawn on Tuesday morning when her stables at Cologne racecourse were placed into quarantine on Monday.
Snow Fairy was also taken out of the race at the weekend.