Alexander Zverev suffered another early Grand Slam exit as the German fourth seed was defeated by Hyeon Chung in five sets, but Dominic Thiem eased into the Australian Open fourth round.
Zverev, still to progress past the fourth round of a major in his burgeoning career, is the highest-ranked men's seed to fall at Melbourne Park so far after Chung became the first South Korean to reach the last 16 at the Australian Open.
Hyeon, who won the inaugural Next Gen ATP Finals last year, is one of the sport's rising stars and the 21-year-old proved the stronger of the two to win 5-7 7-6 (7-3) 2-6 6-3 6-0 in 3 hours and 22 minutes while Thiem beat Adrian Mannarino in straight sets.
"It was a really tough match, I was just trying to play 100 per cent out there," Chung, who will next meet Novak Djokovic, said in his post-match interview on court.
After both players shared the opening four sets in what was a highly competitive match where baseline exchanges dominated the fifth and final set began with Zverev dropping serve with a double fault.
Chung, who had regained the initiative in the match by securing the fourth set, took full control when his German counterpart was broken for a second successive time before the South Korean maintained his composure to clinch victory.
Thiem, who suffered a disappointing second half to the 2017 campaign, proved far too strong for French 26th seed Mannarino, progressing 6-4 6-2 7-5 on Margaret Court Arena in a display in two hours and eight minutes.
The Austrian world No 5, aiming to reach the quarter-finals for the first time, will next meet American Tennys Sandgren who defeated German Maximilian Marterer 5-7 6-3 7-5 7-6 (7-5).
Fabio Fognini reached the last 16 at Melbourne Park for only the second time in his career after a five-set victory over veteran Frenchman Julien Benneteau, winning 3-6 6-2 6-1 4-6 6-3 in three hours on Hisense Arena.
The Italian 25th seed, whose best showing at a Grand Slam is the quarter-finals at Roland Garros in 2011, will next face 19th seed Tomas Berdych who beat Argentine 12th seed Juan Martin del Potro in convincing fashion, winning 6-3 6-3 6-2.
Hungarian Marton Fucsovics, who had never been beyond the first round at a Grand Slam, backed up his impressive victory over 13th seed Sam Querrey with an assured 6-3 6-3 6-2 win over Argentine Nicolas Kicker and awaits defending champion Roger Federer.