Zahra had been set to ride Verry Elleegant at Flemington last year but had to relinquish the seat when suspended for three months for partying with jockeys at an Airbnb rental in breach of COVID-19 protocols.
James McDonald ended up riding the champion mare to victory as a heartbroken Zahra wallowed a thousand miles away in Byron Bay, a tourist spot in northern New South Wales state.
"This time last year I was in Byron Bay and I was getting told off for drinking too much," Zahra said after winning the two-mile handicap at Flemington on Tuesday.
"I felt terrible and I was drinking my way out of it and (my wife) was saying, 'Don’t drink too much'. I said, 'What do you want me to do? My horse just won the Melbourne Cup.'
"It could have been my ride. (It is) redemption day today. It is a miracle.
"For today to come ..it is just unbelievable."
Zahra's maiden Melbourne Cup triumph came after riding Gold Trip, prepared by Ciaron Maher and David Eustace, to a runner-up finish behind Durston at last month's Caulfield Cup, one of the country's most prestigious races.
Rated an 18/1 chance to win the A$8 million ($5.14 million) Melbourne Cup, Gold Trip was saddled with the top weight of 57.5kg on a rain-softened track but held off Emissary in a thrilling sprint before crossing a length and a half clear.
Straight after the race, Zahra said he had been nervous about pushing the horse too soon.
"I literally thought I’m a bit far back here but my one plan was not to be too close because I thought if I spent fuel early I’d be a bit late," he said from the saddle.
"The last 50m I was thinking....'I’m going to win this!'
"It just went forever the last bit."
Zahra paid tribute to his grandfather, a "mad punter" who got him into horse racing.
"I have to shout out to Mum, Dad, and all back in Western Australia," he added.
"If they haven’t had a heart attack, they’d be going crazy right now.
"I’m sure they’re having a shindig somewhere and drinking lots of champagne. Drink some for me."
