Trainer-jockey Johnny Murtagh will not make any decision on a possible Melbourne Cup tilt for Royal Diamond until after his defence of the Irish St Leger on Sunday week.

The consistent seven-year-old was a surprise winner of the all-aged Group One a year ago when trained by Tommy Carmody but is likely to be a leading contender this time around following his victory over the course and distance in last month's Leger Trial.

Royal Diamond was among the initial entries for the Melbourne Cup earlier this week, but Murtagh is keen to take it one race at a time.

Asked about a possible trip to Australia, he said: "His next race will decide that.

"He's all set for the Leger and he's very well at the moment. He came out of his last run really well.

"It looks a good race this year, but it's a mile and six (2800m) at the Curragh and our horse has been there and done it.

"He's pretty versatile ground-wise, so we'll see what happens."

If he does come to Australia, Murtagh has a decision to make with the rules prohibiting him from being a dual licence holder.