Hyeon Chung began playing tennis aged six after his doctor recommended that looking at the green-coloured ball would help his weak eyesight.
Tennessee-born Tennys Sandgren? Well, he never stood a chance with a name like that. He was always going to take up the sport.
But few people, if anyone, gave Chung and Sandgren a chance of clashing in the Australian Open quarter-finals.
That's exactly what the two outsiders will do on Wednesday, though, after cutting a swathe through the Open draw at Melbourne Park.
The 57th-ranked Chung has been especially impressive, backing up his five-set third-round comeback win over world No.4 Alexander Zverev with a thunderous upset of six-time champion Novak Djokovic.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
"I can't believe this. Dreams come true," said an elated Chung after inflicting on Djokovic a first straight-sets defeat at a grand slam in almost a decade - and first in Melbourne since 2007.
Long touted as a star in the making, the bespectacled Korean has taken his game to new levels since winning last year's Next-Gen Finals in Milan, where the world's top eight players aged under 22 assembled for a season finale mimicking the ATP Tour Finals in London.
"I really have a good finish to the season after Milan so I can start really happy this season with the confidence and (feeling) comfortable," the 21-year-said before explaining injuries "every one or two months" since 2015 had stalled his rise up the rankings.
A semi-final on Friday night against either defending champion Roger Federer or Czech veteran Tomas Berdych beckons, but Chung is treating Sandgren with due respect.
And so he should.
Despite having never previously won a main-draw match at a grand slam, Sandgren has taken out 2014 champion Stan Wawrinka and fifth seed Dominic Thiem during his Open charge.
It's been such an unexpected run - after 13 unsuccessful grand slam qualifying attempts - that his mother broke a rib while wildly celebrating back home in Tennessee.
"They were jumping up and down. She fell onto the pool table, cracked a rib. Whoops. I was pretty worried," Sandgren told the New York Times.
The 26-year-old's social media activity has also caused a stir, so much so that Sandgren felt compelled to delete his Twitter posts from the past 18 months after being accused of "links" with alt-right groups.
He denied ever supporting the debunked Pizzagate controversy, where Hillary Clinton was accused on-line of being connected to a child sex abuse ring operating out of a Washington pizzeria in the lead-up to the 2016 US presidential campaign.
Little wonder the journeyman is looking forward to getting back on court and letting his racquet do the talking.
