A narrow winner of the Norfolk Stakes at Royal Ascot in June over the high-class Go Bears Go, Perfect Power then got into all sorts of traffic problems in last month's Richmond Stakes at Goodwood and was beaten just over a length into fifth place.
Khunan was not far off his stablemate when sixth in the Norfolk, and turned the tables in the Richmond when he filled the runner-up spot behind the Alan King-trained Asymmetric - who is also in Sunday's Group One field.
Fahey said: "We've got the two horses in there, and they both go there in good order. We just need a bit of luck now.
"They tell me it's beautiful ground. I wouldn't want it too extreme, but hopefully it will be fine.
"Things didn't go the way we would have liked for Perfect Power at Goodwood, but that's horse racing I'm afraid.
"The other horse wasn't far behind him at Ascot and was in front of him at Goodwood, so it's one apiece."
Asymmetric's Richmond win was his third from just four career starts, his only defeat coming when narrowly beaten by Lusail in the July Stakes at Newmarket.
King said: "He's been very good since Goodwood and has arrived safely.
"He's obviously the quickest two-year-old I've ever trained. That's probably not saying a lot - but he's won his Group Two, and it was either run in the Gimcrack with a penalty or take him to France for a crack at this.
"The forecast looks quite encouraging - the better the ground, the better I think he'll be, so it's very exciting."
The British challenge is completed by Richard Hannon's pair of Armor and Gubbass.
Armor steps up in trip after winning the five-furlong Molecomb Stakes at Goodwood, while Gubbass was third in the Richmond.
Hannon said: "Armor is in great form and it looks like there is some rain on the way which will help him.
"Gubbass won't be out of place, either."
Irish hopes are carried by Gavin Cromwell's Quick Suzy and the unbeaten Velocidad from Joseph O'Brien's yard.
Quick Suzy steps up to take on the colts on her first start since winning the Queen Mary Stakes at the Royal meeting.
"She's in good shape, and we're happy with her," said Cromwell.
"The ground is good to soft and potentially could be good ground come Sunday. Either way it's fine.
"Stepping her back up to six furlongs shouldn't be a problem - it's an easy six in Deauville as well.
"The fillies have a good record in the Morny, and last year's Queen Mary winner (Campanelle) followed up here, so fingers crossed."