"I don't want to get carried away but he might be better than I first thought. I don't think I've ever trained a horse like him with the abilityto adapt that he has."
The Royal Sovereign (1200m) was Rebel Dane's fourth career start and his first in stakes class.
Portelli said the next step would be the Hobartville Stakes (1400m) before the group one Randwick Guineas (1600m) at Warwick Farm in four weeks.
"He looks as if he will get 1400 to 1600m with no trouble on that performance," he said.
"It's exciting."
Collett said his confidence was boosted at the 200m when he felt Rebel Dane give his all.
"I was confident at the 200. I felt him kick," Collett said. "We had a plan to go forward but had to switch to Plan B.
"He's tough and he's got a very big heart him. It was very special, I can't stop smiling."
Group one winning New Zealand colt Sacred Falls started the $2.80 favourite and made some ground to finish fifth after being one of the last out of the gates.
"I thought he ran well," said trainer Chris Waller.
- AAP