People are loving Chung’s sharp glasses at Australian Open
AS A child, Korean tennis star Hyeon Chung had terrible eyesight, so his father suggested he take up tennis to improve his vision.
Chung's father believed encouraging his son to focus on the court's green surface would sharpen his focus.
He probably didn't expect that this throwaway advice would land his son in the history books, as Chung became the first Korean player to ever reach a Grand Slam semi-final on Wednesday afternoon, defeating America's Tennys Sandgren in three sets at the Australian Open.
The 21-year-old is ranked 58th in the world but has become an unlikely fan favourite thanks to his bold playing style and quirky white glasses.
His frames have even earned him a fun nickname - "The Professor".
"I have high-level astigmatism. I have to wear the glasses all the time," Chung told ESPN last December.
"By now they're part of my body so it's not difficult to play wearing them."
In the absence of any homegrown talent to back at the Australian Open, Aussie fans have thrown their support behind the young up-and-comer on social media.
It's unusual for tennis players to wear glasses during play, but there are a couple of famous stars who wear shades.
Serbia's Janko Tipsarevic regularly sports glasses on court.
American tennis legend Billie Jean King also rocked the look back in the day.
Optometry Australia spokesman Luke Arundel said Chung's eye condition astigmatism means he has problems focusing light.
"Instead of the eye being round like a tennis ball, it's shaped a bit more like a rugby ball and that gives him that blurred vision," Mr Arundel said.
"It's unusual to see high performance athletes wearing glasses because it's an additional weight on your head," he said.
"Sometimes they can limit your peripheral vision, so you'll notice Chung wears a wraparound style and it's not a huge deal in tennis because you're facing front on most of the time, hitting back and forth."
Chung's glasses are "almost like swimming goggles", designed to prevent slipping and fogging caused by heat and sweat.
"They have an elasticised band at the back to keep them on and he has rubber nose pads and grips along the temples to keep them stuck to his face," Mr Arundel said.
"You can get issues with glasses like heat and sweat and fogging up."
As for why Chung doesn't wear contacts? Well, every glasses-wearer is different and it's a personal preference.
"In the old days contacts were literally hard pieces of plastic and a little bit of sleep or dust would irritate them," Mr Arundel said.
"These days the technology has come a long way and they're silky soft, oxygen permeable plastic so most people don't have too many issues."