Saddling up just his sixth runner for the season and winning his first, the Mornington based trainer said the win was very special, especially considering the offers the owners had received for the horse.
"What a stage to do it on," Hunter said.
"It's been an incredible journey to this horse. We've believed in him from day one, and it's just great for it to finally come off.
"I'm rapt, especially with the whole team around us and especially the owners, they've knocked back some quite substantial offers for him along the way and give a young trainer like myself a go. I can't thank them enough.
Hunter said Autumn Mystery would indeed be set for the Group 1 Victoria Derby (2500m) on November 1st, provided he pulls up well.
"That'd be the ultimate dream but we'll just see how he pulls up the next few days," Hunter said.
"I think he's got a very big future, but I'd say we'll be heading that way at this stage."
31-time Group One winner Blake Shinn hasn't ridden a Victoria Derby winner to date but said Autumn Mystery possessed all the right qualities to be competitive in a Classic.