Leading contender Brown Panther has been ruled out of Sunday's GAIN Irish St Leger at the Curragh.
Joint-owned and bred by Michael Owen and trained by Tom Dascombe, the five-year-old was a close third in the Group One contest 12 months ago and was being geared towards this event and then the Emirates Melbourne Cup.
However, he spiked a temperature on Thursday and having failed to eat anything during the entire day, Dascombe has had no choice but to rule his Goodwood Cup hero out of a trip to Ireland this weekend.
Dascombe said: "Unfortunately, he won't be running on Sunday.
"We've had him out for a canter this morning and he seems fine, but he didn't eat for some reason and we can't take any chances.
"It's disappointing, but these things happen. Things could be worse, we've still got a horse left and we'll just have to see how long it takes him to recover and aim for something else.
"He's in the Qipco staying race at Ascot on Champions Day (Qipco British Champions Long Distance Cup, October 19) and the Melbourne Cup and both are still options for him.
"If he is going to go to Australia, he doesn't have to go into quarantine until September 26, so we've got a few days for him to recover."
Brown Panther's defection leaves a field of 11 declared runners, with David Wachman's Galileo Rock in the line-up as anticipated as connections consider whether to stay at home or head for Saturday's St Leger at Doncaster.
Last year's Irish Leger hero Royal Diamond is set to defend his crown for trainer-jockey Johnny Murtagh, while Aidan O'Brien saddles both Chamonix and Ernest Hemingway in the one-mile-six-furlong contest.
Ed Dunlop sends globetrotting star Red Cadeaux on the short trip across the Irish Sea.
The seven-year-old is bound for a third tilt at the Melbourne Cup in November and runs at the Curragh instead of heading Down Under early for the Caulfield Cup.
Dunlop said: "His last run was much better and we just thought that he would get more suitable ground at the Curragh (than in Australia).
"The danger is it would be faster at Caulfield, and that would mean he would be having two runs quite close together on quick ground."
The second British contender in this weekend's event is Godolphin's Ahzeemah, last seen winning a thrilling renewal of the Lonsdale Cup at York and another possible Melbourne Cup challenger.
Godolphin racing manager, Simon Crisford, said: "The plan is to run him in Ireland and he is in good form.
"He has been really progressive for us but we will see how he gets on this weekend before making plans."
Dermot Weld runs both Pale Mimosa and Voleuse De Coeurs and the field is completed by John Oxx's Saddler's Rock, the Mick Halford-trained Certerach and Euphrasia from John Murphy's stable.
Certerach makes his first appearance since being narrowly beaten by Ahzeemah in a Group Three at Meydan in early March.
Halford is keeping his fingers crossed his five-year-old is fit enough to do himself justice.
"He had a little setback when he was in Dubai and it is a big ask for him first time back, but there aren't a whole lot of opportunities for him," said the trainer.
"I would have preferred to have got a prep run into him, but it didn't happen.
"We've been aiming at this race for a while and he's as well as we can have him without having had a run beforehand.
"It should be beautiful ground and I'm looking forward to getting him started."