The horse trained by former Australian Rules AFL title-winning coach Denis Pagan was locked neck-and-neck with favourite Young Werther in the final 200 metres but stormed home by more than a length over the fast-finishing Hit The Shot.
Young Werther finished third in the 2,500-metre race for three-year-olds.
"All I was thinking at the 600 was 'don't wake up'," said winning jockey Lachlan King, who won his first Group 1 race. "I've lived this moment in my dreams and it worked out so well.
Pagan who coached Australian Rules side North Melbourne to AFL titles in 1996 and 1999 and only earned his trainer's licence this year, said he could not believe the horse had won the race.
"I'm lost for words," Pagan said. "It's just such an amazing feeling. I thought I was pretty low key yesterday and had a good lunch and maybe a bit too much to drink.
"I didn't expect this. And it's happened."
Social distancing rules meant the racecourse, which typically attracts crowds in excess of 300,000 across the four race days during the week, was deserted with just essential staff, jockeys and officials on site.
The Derby was just one of four Group 1 races on the card on Saturday with Shout the Bar winning the 1600-metres Empire Rose Stakes in a photo finish from pre-race favourite Odeum.
The Chris Waller-trained September Run, ridden by Craig Williams, took out the weight-for-age Coolmore Stud Stakes for three-year-olds over 1,200m shortly before the Derby.
The Kennedy Cantala is the final Group 1 race on the card.
German trainer Andreas Wohler's Ashrun won the Group 3 Lexus Hotham Handicap to secure the last spot in Tuesday's A$8 million Melbourne Cup, the highlight of the Carnival.
($1 = 1.4233 Australian dollars) (Reporting by Greg Stutchbury in Wellington; Editing by William Mallard)