The lightly-raced four-year-old shot to prominence for the famous race when finishing with a rattle into sixth, beaten a little over two lengths, in the Caulfield Cup.
Marmelo, partly sold to Australian interests after winning a Deauville Group Two to offset the cost of travelling to the other side of the world, is likely to be much more at home over another half a mile next week.
However, Morrison has not ruled out dropping in trip with him next season.
"My concern is that you don't have easy races in Group Ones but I hope he comes out as well as he did in the Caulfield Cup," Morrison told www.racing.com.
"We always felt he was the right horse for the race as he's an improving horse and we were happy with how he travelled.
"We were confident he'd run well in the Caulfield Cup and we hope he can do it again.
"Hugh Bowman was very positive about him and the first thing he said was "we're in business", so what more do you need to hear?
"If he stays healthy and sound he could be a Group One horse at home over two miles. He may be like a horse in France called Westerner, he won the Prix du Cadran over two and a half miles but came back to be placed in the Arc and Order Of St George has done similar.
"He's got that class and speed to come back in trip.
"I've always thought he wanted softer ground but he's never not run well on fast ground either."