The High Chaparral colt had a busy first half of 2017 when with John Gosden, for whom he won two Listed races and taking second in the King Edward VII Stakes at Royal Ascot.
He has not been seen since finishing runner-up in the Gordon Stakes at Goodwood, after which he was switched to Cox, and he is one of 31 possibles for the Winter Derby.
"I have been very pleased with Khalidi. He has done well over the winter and is training well at the moment," said Cox.
"He had a quiet second half of last season because of the amount of soft ground we encountered and it was in our minds that, all being well through the winter, the Winter Derby could be a nice starting point this year.
"He had a very productive campaign in the first half of last season and clearly will be in his comfort zone over between a mile and a quarter and a mile and a half.
"I am very much looking forward to getting going with him."
Sir Michael Stoute's Convey and Aidan O'Brien's Deauville are current 5-1 joint-favourites with the sponsors for the Winter Derby, with Utmost, War Decree and Autocratic not far behind.
O'Brien has also entered Lancaster Bomber, Idaho, Clear Skies and War Secretary.
Frankuus, Master The World and Petite Jack are also among 31 contenders at this stage.
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