Michelle Payne arrived in the UK at midday on Tuesday ahead of her ride on Kaspersky in the Queen Anne Stakes - the first race of the week at Royal Ascot on Tuesday.
Payne, who made history in 2015 when she became the first female jockey to win the Melbourne Cup aboard Prince of Penzance, will be based in Newmarket with Kaspersky's Australian-born trainer Jane Chapple-Hyam.
"She arrived at midday," Chapple-Hyam told Press Association Sport.
"She'll be riding three lots out (on Wednesday morning). It's all systems go."
Kaspersky will be one of the big outsiders for the Group One over the straight mile, for which Lockinge winner Ribchester is the short-priced market leader.
However, the six-year-old entire is a Group Two winner in Italy and Germany and was placed at the top level last season.
Formerly trained by Endo Botti, Kaspersky made his debut for Chapple-Hyam when fifth in the Listed Paradise Stakes at Ascot and was second behind Another Touch under 10st in a handicap at Nottingham last time out.
"The horse is absolutely fine. We're a 40-1 shot but I think we'll run better than our price suggests," said the Newmarket trainer.
"He's a lovely horse. He had to give a lot of weight to the winner who is fancied for the Hunt Cup."
Despite having ridden in the UK in the past, Payne incurred an unexpected hitch over her visa requirements and is in contact with the British Horseracing Authority to clarify the situation - though it appears she can ride Kaspersky as the horse is Australian-owned.
A BHA spokesman said: "We are advising Michelle Payne on various matters surrounding a visa application and will continue to work with her on this in the coming days."
Chapple-Hyam added: "I think her visa only permits her to ride Kaspersky.
"We're going to call the BHA and see what the score is."