Saturday, 20 January 2018: South Korea's world No.58 Hyeon Chung has advanced to the fourth round of the Australian Open, beating fourth seed Alexander Zverev in five sets.

German fourth seed Alexander Zverev has been knocked out of the Australian Open in the third round, falling in five sets to South Korean rising star Hyeon Chung.

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The 21-year-old Chung rallied late in Saturday's match, winning the last seven games to clinch a 5-7 7-6 (7-3) 2-6 6-3 6-0 victory in three hours and 22 minutes.

It continues a run of underachievement at grand slams for Zverev, who is yet to live up to his enormous potential on the big stage.

The 20-year-old already has six ATP titles but is yet to reach the quarter-finals of a major from 11 attempts.

The final set statistics make for ugly reading for Zverev. He won just five points, fired off only two winners and made 14 unforced errors compared to just one for Chung.

It is world No.58 Chung's first tour win over a top-10 ranked player, setting up a fourth-round showdown with six-time winner Novak Djokovic or Spain's Albert Ramos-Vinolas.

The reigning Next Gen Finals champion has seen off two Zverevs at Melbourne Park after Alexander's older brother Mischa's retirement during their first-round match.

"It was (a) really tough match again today," Chung said.

"Alex Zverev is a really good player. I'm just trying to play 100 per cent on court.

"I play Novak like two, three years ago in Rod Laver (Arena). And I have one more chance to play with him if he wins tonight."