Connections of Ortensia admit they will be "devastated" if William Buick is unable to ride the mare in Saturday's Betfred Sprint Cup.
Paul Messara's Australian speedball was a disappointment in the King's Stand Stakes at Royal Ascot, but ran more encouragingly when ridden by Buick for the first time to finish fourth in a heavy ground July Cup at Newmarket.
The jockey has since guided the mare to win the King George Stakes at Glorious Goodwood and the Group One Nunthorpe Stakes at York, but it remains uncertain whether he will be available for her next start at Haydock.
Buick is committed to riding Nathaniel for his boss John Gosden in the Irish Champion Stakes at Leopardstown on Saturday, but may travel to Haydock first before flying to Ireland.
Leah Gavranich, who has stayed with Ortensia throughout the summer in Newmarket, is praying that is the case.
"William is very important. I'd probably go as far to say that he has a better partnership with the mare than anyone else that has ridden her," she told At The Races.
"He just seems to understand the horse a lot better and early on in her races he doesn't push her around and gives her the time to find her feet. I think that really tells at the end of her races and he gets quite a tune out of her.
"Hopefully he's free to ride them both, but obviously he has to ride Nathaniel for John Gosden, so we'll be looking around for a back-up plan I'm sure.
"There's a few things in the pipeline, but I'll definitely be devastated if William can't take the ride."
Gavranich admits potential replacements for Buick have been discussed, but she is not naming names.
"There are a few other names being thrown around, but I'll have to leave that under wraps for now," she said.
Ortensia steps up to six from five furlongs on Merseyside this weekend, but Gavranich does not envisage the extra distance being a problem and is happy with her pride and joy's condition.
She said: "She won a Group One over six furlongs in Australia and hopefully she can show that same turn of foot.
"She definitely felt the run (at York), there's no doubt about that. She just took a day or so to physically look a lot better, but she never left an oat one day, she's such a great doer and has a great constitution.
"I'm very happy with where she's at at the moment. She's very fresh and well and really loving life. Hopefully she can show she's as good over six (furlongs) as she is over five."