Twelve-time Grand Slam winner Novak Djokovic was sent tumbling out of the Australian Open by Korean giant-killer Chung Hyeon on Monday, while ice-cool Roger Federer roared into the quarter-finals.

The Serb, who was returning from six months out with a right elbow injury, was clearly in pain as his hopes of a seventh Melbourne Park title were extinguished on Rod Laver Arena 7-6 (7/4), 7-5, 7-6 (7/3).

Chung’s reward is a last-eight clash with unheralded American Tennys Sandgren, who upset Austrian fifth seed Dominic Thiem 6-2, 4-6, 7-6 (7/4), 6-7 (7/9).

The Big Story

Hyeon knocks out six-time champ Djokovic

South Korean star Chung Hyeon dumped six-time champion Novak Djokovic out of the Australian Open in the fourth round.

The 21-year-old beat the battle-weary Serb, who was clearly in pain as he stretched for balls, 7-6 (7/4), 7-5, 7-6 (7/3) and will face American Tennys Sandgren in the quarter-finals.

Federer eases into quarter-finals

Defending champion Roger Federer charged into his 14th Australian Open quarter-final with a straight-forward win over Hungary’s Marton Fucsovics.

The Swiss second seed was too strong for the 80th-ranked Fucsovics, winning 6-4, 7-6 (7/3), 6-2 in just over two hours on Rod Laver Arena. Federer will now face long-time rival Tomas Berdych in the last eight, holding a 19-6 lead over the Czech dating back to 2004.

It will also be Federer’s 52nd Grand Slam quarter-final, the most in the post-1968 Open Era.

Sandgren’s dream run continues

Unheralded American Tennys Sandgren upset Austria’s fifth seed Dominic Thiem over five sets to advance to the quarter-finals of the Australian Open on Monday.

The 97th-ranked Sandgren won 6-2, 4-6, 7-6 (7/4), 6-7 (7/9), 6-3 and will face either Novak Djokovic or Chung Hyeon in the last eight.

Kerber ends Hsieh Su-wei run to reach QF

Angelique Kerber kept her hopes of a second Australian Open title alive with a battling come-from-behind 4-6, 7-5, 6-2 victory against Taiwan’s tenacious Hsieh Su-wei on Monday.

Germany’s Kerber, the 21st seed, will play Madison Keys for a place in the semi-finals after the American 17th seed steamrollered French eighth seed Caroline Garcia 6-3, 6-2.

Shot of the day

From the sidelines

Davis marathon leaves Halep sleepless

Simona Halep said she was close to playing “100%” despite her aching body giving her sleepless nights as she reached the Australian Open last eight Monday.

Halep has spent a shade under eight hours on court in four matches so far, including an epic 3hr 44min against Lauren Davis on Saturday which the Romanian won 15-13 in the final set.

“First day after the (Davis) match was pretty OK,” the top seed told reporters after a 6-3, 6-2 victory over unseeded Naomi Osaka of Japan in 81 minutes.

“Last night was really tough. I couldn’t sleep. I had pain everywhere.

“But I slept before the match two hours, and worked perfect, perfect hours. I was, like, fresh after that. I felt good.”

What’s the plan to defeat Roger?

“If there is any plan or any key to success then I would like to know that,” was Tomas Berdych’s reply to reporters’ oft-asked question about his chances against Roger Federer in the quarter-final.

The Swiss 19-time Grand Slam champion holds all the aces with a one-sided 19-6 record and Berdych knows he faces another tough challenge if he is to progress in the year’s opening Grand Slam.

“I’m definitely going to go out there, try my best, try to play good tennis, and believe myself that I can do it.

“I did it in the past, and also, I did it in the slams, so I know how it is to beat him for the best-of-five sets.

“But obviously he’s an extremely tough opponent. I will just to go out there and swing at some balls.”

Federer plans dinner with the missus; Mirka has other plans

Roger Federer these days are seen having fun on court and off it. Whatever he does, he seems to enjoy it. At 36, he jokes, laughs, challenges The Rock and gets to the Australian Open quarter-finals without dropping a set. After his three-set win, Jim Courier quizzed him about his evening plans.

“So now you are done. It is almost 5:45pm. You will have press conferences, massage and all that stuff but you actually get a night off here. Is that dinner and dancing with Mirka? What is the game plan for tonight?” Courier asked.

Federer: “(We’ll) probably be busy until about 9pm. We might go out for a nice dinner if she’s in the mood ... but she has left already so she has other plans!”

Quotable Quotes

“Oh, this one was the biggest joke of a point maybe I have ever played.”

–Roger Federer on this point:

“Wow, this is hopefully real, you know. If I wake up now, I’m going to be real upset (laughs)”
Tennys Sandgren at the post-match press conference after defeating the fifth seed Dominic Thiem.

“I have pretty much been binging Netflix shows. “Grace and Frankie” is back on.”

Madison Keys reveals her post-match activities.