John Gosden will still have a hand in Sunday's Prix de l'Arc de Triomphe with Nathaniel's little sister Great Heavens a late entry for the race at Longchamp.

Not sighted since her brilliant display to win the Irish Oaks in July, the Lady Rothschild-owned filly was expected to line up in the British Champions Fillies' And Mares' Stakes at Ascot on October 20.

However, with Nathaniel a significant withdrawal earlier in the week after suffering a setback, Rothschild and Gosden have decided to add Great Heavens to the field for Europe's premier middle-distance prize.

Bayrir and Saonois have also been supplemented as anticipated, while Reliable Man is the only withdrawal, leaving a field of 18 possible runners.

Great Heavens has yet to reach the same kind of heights at this stage and Gosden does not see her as a like-for-like replacement.

The trainer has hailed the owners for stumping up 100,000 euros ($A128,090) to add her to the Longchamp showpiece.

"It wasn't a straightforward decision but she's working nicely and is in good order," Gosden said.

"They had significant rain in Paris overnight, so a few things weighed in favour of running and I think the owners have made a very sporting decision to let her take her chance."

William Hill make Great Heavens a 12-1 shot to claim Arc glory, with Japanese star Orfevre and Aidan O'Brien's Camelot the joint-favourites at 11-4.

Gosden said he was much happier with Nathaniel who was ruled out of the Arc due to a temperature.

"He's been out this morning and seems much brighter and happier in himself," he said.

"He'll have another (blood) test on Saturday and hopefully things will be back to normal. I am certainly much happier with him now than earlier in the week."