Aidan O'Brien has four horses in the mix for the Prix de l'Arc de Triomphe with plans likely to be firmed up next week.

The champion Irish trainer is seeking a second Arc after Dylan Thomas in 2007, and at this stage can call on Ruler Of The World, Leading Light, Kingsbarns and Camelot, although ground conditions are crucial to the latter.

Epsom Derby winner Ruler Of The World stated his case when narrowly beaten in the Prix Niel while Queen's Vase winner Leading Light landed the English St Leger at Doncaster to earn a possible supplementary entry for the Longchamp showpiece on October 6.

"At the moment we have in the mix Ruler Of The World, Leading Light, Camelot and Kingsbarns. Camelot will only run if the ground is good or better," O'Brien said.

"Leading Light will have to be supplemented and he will work next week before any decision is made. He's lazy but is not short of class."

One-time Derby favourite Kingsbarns has had just one run since winning last year's Racing Post Trophy. He was eased down when last of six in the Irish Champion Stakes at Leopardstown.

"It would be a big call after Leopardstown and he's also in the Champion Stakes at Ascot," O'Brien said.

O'Brien added that he was likely to be represented by Wonderfully in the Shadwell Fillies' Mile at Newmarket on Friday but that Darwin and Cristoforo Colombo were set to bypass the Joel Stakes on the same card.