Auckland ASB Classic quarter-finalist Chung Hyeon has continued to defy his age and ranking, stunning six-times Australian Open champion Novak Djokovic to become the first South Korean to reach a tennis grand slam quarter-final.
Chung turned in a relentless display of high energy tennis to knock Djokovic out in straight sets in Melbourne.
Chung, ranked 58th in the world, absorbed everything the former world number one threw at him and returned it with interest while Djokovic was hampered by the recurrence of the elbow injury that sidelined him last year.
The 21-year-old Chung will meet Tennys Sandgren in the quarter-finals after the 97th-ranked Tennessee native dispatched fifth seed Dominic Thiem in five sets to continue his dream debut run.
Chung beat Sandgren in the first round of the ASB Classic earlier this month in a three set thriller, a match Sandgren has credited for adding a new-found steely resolve to his game.
Defending champion Roger Federer sauntered past Hungarian Marton Fucsovics to reach the 52nd grand slam quarter-final of his career where he will meet big-serving Czech Tomas Berdych.
Women's top seed Simona Halep shook off ankle pain to sweep past Japanese Naomi Osaka 6-3 6-2 in 79 minutes and stay in the hunt for a maiden grand slam title.
Halep will meet Karolina Pliskova in the quarter-finals after the Czech sixth seed rallied from a set down to see off compatriot Barbora Strycova in the day's last match.
Former champion Angelique Kerber fell back on raw power to overcome the unorthodox game of world number 88 Hsieh Su-wei 4-6 7-5 6-2 and reach the last eight where she will meet U.S. Open finalist Madison Keys.