Just a week shy of the first anniversary of his maiden European Tour victory at the ISPS Handa World Super 6 Perth, Fox mastered very high winds at 13th Beach Golf Club to card two eagles and four birdies in a round that was the lowest of the day by three shots.
The 33-year-old has gone lower on the European Tour, signing for a 63 at the Aberdeen Standard Investments Scottish Open in 2018 just a week after losing a play-off at the Dubai Duty Free Irish Open hosted by the Rory Foundation.
But with the wind making scoring very difficult on the Beach Course on day four, Fox revealed he felt his effort in Geelong was one of his very best.
"That's probably the best round of the last 30 years for me," he said. "Comfortably probably the best round I've played in a tournament.
"I've been playing pretty good the last couple of weeks, I played great the weekend in Saudi and didn't really get much out of it and played really good most of this week.
"You're not supposed to shoot 64 on a day like today but I'll certainly take it.
"I decided today I was going to take it on and if I shot four over and finished down the bottom it didn't matter. I kept that aggressive mindset throughout.
"If you told me I'd shoot 64 and finish second, I certainly would have taken that at the start of the day."