Azamour and Grey Swallow are disputing favouritism for Saturday's Boylesports Irish 2000 Guineas following the shock withdrawal today of One Cool Cat.
Aidan O'Brien's colt, who has been ruled out of the Curragh Classic with a "low-grade infection", had been a top-priced 5-2 chance for the race but was not among the eight final declarations this morning.
A spokesman for Ballydoyle said: "He had a routine scope this morning and he was found to have a low-grade infection. The trainer wants to give him more time."
One Cool Cat flopped when favourite for the UltimateBet.com 2000 Guineas at Newmarket earlier this month when he finished 13th of 14, but he was later found to be suffering from an irregular heartbeat.
"We'd hope to have him back for Royal Ascot. We'll probably just give him an easy week or 10 days and hopefully train him for Ascot," O'Brien said.
O'Brien will now rely on Grand Reward, the mount of Jamie Spencer, and Newton in the €400,000 contest.
"Grand Reward is a very good colt and he didn't have the best of luck when he was racing last year but we always thought he was a very nice horse," the Ballydoyle trainer added. "We are hoping for a good run."
Azamour and Grey Swallow finished third and fourth respectively behind Haafhd in the 2000 Guineas at the beginning of the month and are both priced up at 13-8 by Coral and Ladbrokes. Paddy Power go 13-8 Azamour and 9-4 Grey Swallow.
Grey Swallow's trainer Dermot Weld also runs Hayburn Street.
Betting(courtesy of Paddy Power): 13-8 Azamour, 9-4 Grey Swallow, 9-2 Leitrim House, 8-1 Bachelor Duke, Grand Reward, 25-1 Amarula Ridge, Newton, 50-1 Hayburn Street.