Ante-post favourite Deacon Blues is "unlikely" to run in Saturday's Betfred Sprint Cup at Haydock after failing to sparkle in his final workout.
The four-year-old was a seven-length winner in Ireland last time, but trainer James Fanshawe was not satisfied with his work on Wednesday morning and the gelding subsequently scoped dirty.
Fanshawe said: "He worked a bit flat this morning in his final blowout and when we scoped him, there was some mucus so he's unlikely to run on Saturday."
Deacon Blues won the Wokingham Stakes at Royal Ascot in June and was due to graduate to Group One level for the first time on Merseyside following a comfortable Group Three success at Newbury and a demolition job at the Curragh at the same level.
Fanshawe continued: "His work just lacked his usual sparkle and we have just two days now to the race, so he's unlikely to run.
"There was quite a bit of mucus there."
Deacon Blues holds entries in the Park Stakes at Doncaster on September 10 and the Renaissance Stakes at the Curragh one day later, but Fanshawe has a return to Ascot in his sights.
"We were hopeful of running well at Haydock and the next big sprint after that is the Qipco British Champions Sprint Stakes at Ascot on October 15, so the aim is to get him back bouncing for that," added the Newmarket handler.
While Deacon Blues is unlikely to line up at Haydock, Fanshawe has another strong contender in Golden Jubilee Stakes winner Society Rock.
The four-year-old was a shock scorer at Royal Ascot and has since finished second in the Prix Maurice de Gheest at Deauville.
Fanshawe added: "Society Rock is still in there. He's fine, and the plan is to run."
Society Rock was a general 7-1 chance before the doubts about his stablemate emerged.