“We saved like four match points in the semifinals,” Chung said this week in the players’ restaurant at Melbourne Park. “If I lose that match, maybe I am not here now. I would have to go to the army.”

Chung said he later served in the military for a few weeks, which did not pause his tennis career for long. It is not beyond the realm of possibility that Chung can win the Australian Open, too, after defeating three seeded players, including the six-time champion Novak Djokovic in the fourth round.

“Look, I’m very excited to play Chung,” said Federer, 36, who will face an opponent 15 years his junior at this late stage of a major tournament for the first time. “I thought he played an incredible match against Novak. To beat him here is one of the tough things to do in our sport, I believe. I know that Novak maybe wasn’t at 110 percent, but he was all right. He was giving it a fight till the very end. To close it out, that was mighty impressive.”

Djokovic was definitely not at the peak of his elastic powers, coming off a six-month break and still suffering from right elbow pain. But he posed a serious challenge to Chung, who was also facing the mental barrier of playing his idol in the same stadium where Djokovic beat Jo-Wilfried Tsonga in 2008 to win his first major title.

That was the first Grand Slam final that Chung remembered watching on television, but he had been pretending to be Djokovic for years in makeshift matches against his older brother, Hong, in a parking lot in front of the family’s home and elsewhere.