Connections of English horse Spanish Mission are more worried about the prospect of soft ground than the quality of the opposition ahead of the $1 million Jockey Club Derby Invitational Stakes at Belmont in New York.

The David Simcock-trained three-year-old heads to America this weekend in preference to Doncaster next week for the St Leger.

He won a notable trial for the oldest Classic at Newmarket, the Bahrain Trophy, but his owners, the American-based Team Valor and Earle Mack, have decided to bypass Doncaster.

"There's rain in the forecast for a couple days, and who knows if (Hurricane) Dorian will come up the coast. Long Island is up the coast," Team Valor's Barry Irwin told www.bloodhorse.com.

"The weather is our big concern. The horse versus the competition and the conditions, we feel very good about that.

"Even though he has run a mile and a half and more, he's a versatile horse.

"When he won his last race, Jamie Spencer told us, 'don't just think he's a stayer - today it wouldn't have mattered what the distance was'."

Whatever the outcome at Belmont, the Melbourne Cup is looming large on the horizon.

"With horses by Noble Mission, most of them look like the older they get, the better they will get," Irwin said.

"This trainer has been telling me from day one that no matter what he does this year, Spanish Mission will be better next year and even better the year after that.

"We're looking at a horse we can campaign until he's at least five, with that big race in Australia in mind. One of our plans is that we hope he can be a Melbourne Cup horse, which is a race Earle and I would love to win.

"Ideally, he could run in it at five or six, but if he continues to improve, he could do it next year."