Race favourite Teofilo has suffered a "training setback" but remains on target for the 2000 Guineas at Newmarket on 5 May.
The unbeaten Galileo colt will be restricted to walking and swimming for one week because of a problem.
"Teofilo has had a training setback. When he trotted yesterday [Monday] afternoon he showed slight discomfort," said trainer Jim Bolger.
"A further statement on his condition will be issued early next week."
Speculation surrounding Teofilo on Monday saw his price drift on the exchanges and several bookmakers also suspended betting on the first Classic of the season.
Sponsors Stan James have now reopened their market on the race but have eased Bolger's charge slightly to 6-4.
"It looks as if the colt will miss a week of work, which equates to a couple of gallops"
"Having suspended our market when the adverse rumours about Teofilo did the rounds, we have now gone back up and eased the favourite out to 6-4 from 11-8," said spokesman Neil Morrice.
"As sponsors, we are delighted to hear that there was insufficient substance in the rumours about Teofilo's well-being to jeopardise his appearance in our race on 5 May.
"It looks as if the colt will miss a week of work, which equates to a couple of gallops.
"But despite this, there is no reason why Jim Bolger shouldn't have him ready to run a fortnight on Saturday."
Stan James 2000 Guineas
Sponsors bet: 6-4 Teofilo, 9-2 Dutch Art, 7 US Ranger, 15-2 Strategic Prince, 14 Mount Nelson, Haatef, 16 Adagio, 20 bar.