Caulfield Guineas favourite Astern will miss his scheduled lead-up to the Group One race because of an elevated temperature.

Trainer John O'Shea said the Golden Rose winner was treated for the temperature on Sunday and would not travel to Melbourne for Saturday's Guineas Prelude.

"The horse was found to have an elevated temperature this afternoon," O'Shea said.

"His treatment will compromise his travel plans and as a result he won't be going to Melbourne for the Guineas Prelude."

Godolphin also said in a statement that James McDonald, who was to have ridden Astern, would remain in Sydney on Saturday to ride at Rosehill.