Tomorrow's ante-post favourite for the Group 1 Sussex Stakes, Rosallion, has been ruled out due to a respiratory infection.

The Richard Hannon-trained three-year-old was a general 5/6 to shot to claim a fourth top-level success, having accounted for the rewording Henry Longfellow and Notable Speech in great style in the St James's Palace Stakes at Royal Ascot last month.

Rosallion's defection has seen Aidan O'Brien's Henry Longfellow, who finished runner-up to him at Royal Ascot, jump the head of the betting. Paddy Power now makes Henry Longfellow their 6/4 market leader, with Charlie Appleby's 2000 Guineas hero a 13/8 chance to bounce back from his flop in the St James's Palace Stakes.

A statement on Richard Hannon's website said: "We are very disappointed to release the news that Rosallion will be a non-runner in the Sussex Stakes tomorrow at Goodwood. He has got a slight respiratory infection and just isn't his usual self at home.

"It has not been a difficult decision to make, considering how incredible he has been for the whole yard and how much he means to the team and to his owner. We have to put his welfare at the very top of our priorities.

"He will miss this one, but there is still a big chunk of the season to come, where he will be able to be the horse we all know and love."