Chung beat Tennys Sandgren of the United States 3-0 (6-4, 7-6 (7-5), 6-3) in the quarterfinals match at Rod Laver Arena in Melbourne. He will next face Roger Federer in the semis on Friday. Federer, who boasts 19 Grand Slam singles titles, blanked Tomas Berdych 3-0 (7-6 (7-1), 6-3, 6-4) to reach the last four.
This was Chung's second encounter with Sandgren. A couple of weeks ago, he defeated the 26-year-old American in the first round of the ASB Classic in Auckland, New Zealand, 2-1 (6-3, 5-7, 6-3).
Both players had produced their own fairy tales at the season's first Grand Slam event before their showdown. While 97th-ranked Sandgren collected victories against 2014 champion Stan Wawrinka and fifth seed Dominic Thiem, 58th-ranked Chung stunned fourth seeded Alexander Zverev and six-time Australian Open winner Novak Djokovic to become the first Korean -- man or woman -- to play in a Grand Slam quarterfinals.
In a battle between two surprising quarterfinalists, Chung got off to a good start by wrapping up the first set in 37 minutes. The pair held their serves to open the set, but Chung broke Sandgren in the third game and kept his lead until the end.
The second set was a different story, as the two went to a nail-biting tiebreak. Chung earned a quick 2-0 lead, until Sandgren took three straight games with his powerful serves and aggressive plays that drew unforced errors from the 21-year-old Korean.
Chung later evened the score at 5-5, but Sandgren collected three forehand winners in the next game to retake the lead. Chung then forced the tiebreak, as he comfortably held his serve.
In an intense tiebreak, Chung drew first blood, but Sandgren later went up 5-4 with a forehand winner. Sandgren needed two points to even the match, but Chung reeled off three straight points from there to seal the set.
Chung and Sandgren held their serves to start the third set. Chung again took the driver's seat by winning three straight games for a 4-1 lead. After taking one game each, Chung was up 40-0 and only need a point to wrap up the match. Sandgren, however, didn't go down easily, as he created a chance for a break point from there.
The two later engaged in a long rally that consisted of 31 shots, with Sandgren finding the net to bring the game to deuce. On the next match point, Sandgren showed incredible moves in front of the net to entertain fans at the arena as he fended off two close range shots from Chung.
Chung finally collected his semifinal seat as he advanced on his sixth match point.
With the latest victory, Chung became the first Asian in 86 years to reach the semifinals at the Australian Open since Japan's Jiro Sato did so in 1932.
He is also projected to crack the top 30 in the upcoming Association of Tennis Professionals rankings. Chung previously reached as high as world No. 44.
Chung admitted he lost his concentration in the last game against Sandgren.
"At 40-0, I was thinking about what to say in (the) ceremony,”he said in a post-match interview on the court.
When asked about whether he would prefer Federer or Berdych in the next round, Chung said he doesn't really care.
"I don't know," he said. "It's 50-50 ... I don't care."
Chung also spoke in Korean to fans in his homeland and to those who came to Rod Laver Arena to see his performance.
"My competition isn't over, so please keep supporting me," he said. "I'll see you guys on Friday."(Yonhap)