Trainer Aidan O'Brien said Monday night that Rock of Gibraltar, winner of seven consecutive group I stakes, would be withdrawn from Saturday's Queen Elizabeth II Stakes at Ascot if the ground remains firm and could close out his career in the Breeders' Cup Classic."We are making everyone aware of the situation regarding Saturday," O'Brien said in the Racing Post. "Rock of Gibraltar and Hawk Wing will both be declared at the 48-hour declaration stage but only one will run. If Rock of Gibraltar doesn't run at the weekend he will go straight to the Breeders' Cup but it hasn't been decided yet for which race. We haven't ruled out the Classic. He will be going for one of those races, the Mile or the Classic. We haven't decided yet which one."We want to run Hawk Wing on fast ground, so if the ground is suitable, the likelihood is that he, and Sholokhov, will run in the Queen Elizabeth. If the ground changes then Rock of Gibraltar, who doesn't seem to mind the ground and who has won on soft, would probably run instead and be joined in the line-up by Sahara Desert."Rock of Gibraltar, who defeated Hawk Wing by a neck in the 2,000 Guineas, has not run beyond a mile, while Hawk Wing has won the 10-furlong Eclipse Stakes, and placed in the English Derby and Irish Champion Stakes. It had been expected that Hawk Wing, a son of Woodman, would be Ballydoyle's Classic hope.Rock of Gibraltar, owned by Sir Alex Ferguson and Susan Magnier, broke Mill Reef's European record for consecutive group I victories when he captured the NetJet Prix du Moulin at Longchamp, defeating last year's Breeders' Cup Filly & Mare Turf winner Bank's Hill.