Carson is delaying a decision on whether to partner Harayir and leave his understudy, Richard Hills, to ride the John Dunlop-trained Shahid, until he has assessed the impact of possible rain at the track.
Speaking at a rainy Ascot last night, Carson said: "I think that it will be the filly but we'll wait and see. I keep looking at the sky and I might change my mind."
Carson, who rode his 100th winner of the season at Nottingham on Monday, will be hoping his judgement is spot on this time after choosing Aqaarid ahead of Harayir in the fillies' Classic at Newmarket.
"In fairness to me, the one I rode didn't run her race, otherwise she would have come home alone," Carson said. "It was unfortunate but I was on the right horse on the wrong day."
The same feeling will affect those punters who have been tempted into snapping up the early odds about Espartero, the favourite for the Ayr Gold Cup on 16 September. He is likely to miss the race.
His trainer, Sir Mark Prescott, said yesterday: "Espartero is more likely to run in Ireland, where his target would be the Flying Five at the Curragh. My other Ayr entry, Quiz Time, is also likely to miss the race."
Espartero was made 12-1 clear favourite with both the Tote and William Hill and 14-1 joint-favourite with the sponsors, Ladbrokes, for the Ayr race after yesterday's publication of the weights.
Top Banana, the other joint-favourite, finished second in last month's Stewards' Cup at Goodwood, with Espartero fourth. The winner, Shikari's Son, is also among the Ayr entries. Mark Johnston's Double Blue, a heavily backed 4-1 favourite last year when finishing 11th and winner of the Great St Wilfrid Handicap at Ripon last Saturday, is 16-1.Reuse content