Dzumhur pulled the pin down 6-2 3-0, having required treatment on his left hamstring while down 4-1 in the first set. The Bosnian seventh seed grabbed at his hamstring at the completion of an earlier point before being treated on the side of the court.

But not before being blown off the court by 18-year-old de Minaur, ranked 167 in the world, who added another scalp to his 2018 list which also includes Milos Raonic and Fernando Verdasco. In the last week and a half he's beaten four top-50 ranked players.

He'll now look to continue his stellar run in Thursday's quarter final against Feliciano Lopez, which follows on from his deep run in the Brisbane International and last month's Australian Open wildcard playoff victory.

"I always knew I had the level, but I didn't think I had the belief," de Minaur said.

"Now I've got that belief in me that I can go toe to toe with lots of guys out there. So I'm going into every match, you know, believing in myself and believing in my ability.

"The Australian wildcard playoff, that's when I first thought that my level was in really good nick. I did not drop concentration at all during that whole tournament, I have just been able to keep that level going throughout the whole Australian summer.

"I'm enjoying every second of it. It's great. I'm playing some unbelievable tennis, and, you know, I just want to keep it going, really."

It's the mental side of his game that de Minaur believes has underpinned a sensational start to 2018.

At just 69kg dripping wet, de Minaur prefers the refuge of the baseline during the majority of his points yet he boasts a power game usually not present in a man of his weight division.

But it's his composure which outshines his years, an iron-willed mental capacity that has him determined to win every point and protects him from the pressure of an expectant home crowd on centre court.

De Minaur employs a series of breathing exercises during tennis matches, to which he attributes his rapid rise in 2018.

"You know, breathing helps a lot, I think it's more about just trying to win every point...not letting go because of the scoreline or anything, you have to play every point and try to win every point," de Minaur said.

"That's what I'm trying to do when I'm out there on court, and it's really helped me to stay on my opponents both physically and mentally.

"I take a couple of deep breaths, I'll focus on what I want to do in that game, go through every single point.

"It's been working for me. That's some work I have been doing with a psychologist back in Spain. He's always told me to do it, and now I'm finally doing it.

"Now I realise how much better my game is, thanks to those simple techniques."

Earlier on Italian veteran Paolo Lorenzi pulled off the biggest upset in the men's draw so far, brushing aside Spanish top seed Albert Ramos-Vinolas 6-3 7-5 in the second round.

The world number 22 required treatment for a leg issue in the second set, but returned to the court only to fall to his 36-year-old opponent.

Lorenzi will now play qualifier Daniil Medvedev for a place in the semi-finals after the Russian proved too good for American Jared Donaldson.