Australian Open day eight

MELBOURNE (Reuters) - Chung Hyeon turned in a relentless display of high energy tennis to stun six-times Australian Open champion Novak Djokovic 7-6(4) 7-5 7-6(3) on Monday and become the first South Korean to reach a grand slam quarter-final.

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.

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.

READ MORE

Chung gives Djokovic taste of his own medicine

Djokovic to reassess options over elbow injury

Young gun Chung blazes trail for South Korea

Sandgren topples Thiem to keep Melbourne dream alive

Sandgren wants more meat off grand slam bone - coach

Pliskova battles back to reach quarter-finals

FACTBOX-Tennis-Rafa Nadal v Marin Cilic

Halep beats pain, Osaka to reach quarter-finals

Federer makes light of day shift to ease into last eight

Nadal braced for tough Cilic test in Melbourne showdown

Kerber back in the big time after tough year

American Keys storms into last eight

Injury-free Berdych sweeps past Fognini

Order of play on Tuesday

Highlights of Monday's eighth day of the Australian Open, the first grand slam tournament of the year (times in GMT):

1435 PLISKOVA BATTLES BACK AGAINST COMPATRIOT STRYCOVA

Czech sixth seed Karolina Pliskova fought back from a set down to beat compatriot Barbora Strycova 6-7(5) 6-3 6-2 in the day's last match.

Pliskova will face world number one Simona Halep in the quarter-finals.

1353 DJOKOVIC FRUSTRATED BY INJURY

Novak Djokovic spoke about the recurrence of the elbow injury that sidelined him last year after he was beaten in straight sets by South Korean Chung Hyeon.

"It's frustrating when you have that much time and you don't heal properly. But it is what it is. There is some kind of a reason behind all of this... Today was one of those days where, unfortunately, it was too much to deal with," he said.

1348 CHUNG IN DREAMLAND AFTER DOWNING DJOKOVIC

Chung Hyeon said his dreams came true after he beat his idol Novak Djokovic to reach his first grand slam quarter-final.

"I'm just looking for Novak, Roger, Rafa. They're all my role model, my idol. I'm just happy to play with Novak again. I'm just honoured to see him again on the tour. Today my dreams come true," Chung said.

1135 RELENTLESS CHUNG STORMS PAST DJOKOVIC

Chung became the first South Korean to ever reach the quarter-finals of a grand slam when he pummelled his way past Djokovic 7-6(4) 7-5 7-6(3) in one of the biggest shocks of the tournament.

The six-times champion looked dazed as his 21-year-old opponent turned in a relentless display of high-energy tennis to set up a quarter-final meeting with American Tennys Sandgren.

1050 SANDGREN RELISHING ELEMENT OF SURPRISE

Tennys Sandgren on how being a relative unknown is giving him the edge in Melbourne. The American beat fifth-seed Dominic Thiem to reach the quarter-finals and continue his dream Australian Open debut.

"I have that going for me, that guys may not know what to expect," Sandgren said in an on-court interview. "I'm using that to my advantage and just trying to ride the wave. It's my first main draw, and now I am in the quarter-finals."

1000 GIANT-KILLER SANDGREN UPSETS THIEM

American Sandgren has knocked out yet another top 10 seeded player, beating Austrian Thiem 6-2 4-6 7-6(4) 6-7(7) 6-3 to progress to the quarter-finals of a grand slam for the first time.

The 26-year-old, who beat ninth seed Stan Wawrinka in the second round, will take on the winner of the match between former champion Novak Djokovic and Next Gen ATP Finals winner Chung Hyeon.

0740 HALEP ON HER INJURY

Top seed Simona Halep on overcoming her ankle injury, sustained in her first round victory over Destanee Aiava, to beat heavy-hitting Naomi Osaka and reach the quarter-finals.

"This tournament looks like a marathon for me," Halep said in an on-court interview. "The injury is still there, I feel it but I try not to think about it, trying to enjoy the moment and give everything..."

0735 HALEP SURGES PAST OSAKA

World number one Halep remained on course for a maiden grand slam title when she progressed to the quarter-finals of the Australian Open with a 6-3 6-2 win over Japan's Osaka.

The Romanian has reached the last eight at Melbourne Park for the third time and will next face Czech Karolina Pliskova.

0640 FEDERER INTO QUARTERS

Defending champion Roger Federer has progressed to the last eight of the Australian Open for the 14th time after a 6-4 7-6(3) 6-2 victory over Hungarian Marton Fucsovics.

The world number two, who has never lost a quarter-final at Melbourne Park, will take on Czech 19th-seed Tomas Berdych next.

0425 KERBER REFLECTS ON A TOUGH MATCH

German Angelique Kerber gave credit to Hsieh Su-wei for a thrilling fourth-round encounter on Rod Laver Arena.

"First of all, credit to her. She played unbelievable. She was hitting the balls, I don't know. I was running everywhere and she always had the answer. I was everywhere," the former champion said after sealing a quarter-final berth.

0417 KERBER BATTLES PAST HSIEH

Former champion Kerber recovered from a set down to beat Taiwan's Hsieh 4-6 7-5 6-2 in the fourth round.

Kerber, the only remaining former grand slam winner in the women's draw, will face American Madison Keys in the quarters.

0405 BERDYCH EASES INTO QUARTER-FINALS

Czech Tomas Berdych beat Italian Fabio Fognini 6-1 6-4 6-4 to progress to the last eight of the Australian Open for the seventh time in eight years.

The 19th-seed will take on title favourite Roger Federer next.

0210 KEYS HAPPY TO BE BACK

Madison Keys missed the 2017 Australian Open due to a wrist injury and is relishing her winning return to Melbourne Park.

"It definitely made me realise how much I love it and how much pressure I put on myself. Missing this last year, I feel like I'm playing without pressure and just going out and playing my game," the American said after her fourth-round victory.

0135 AMERICAN KEYS THRASHES GARCIA TO REACH LAST EIGHT

Keys, the last surviving American woman at Melbourne Park, thrashed eighth seed Caroline Garcia 6-3 6-2 to reach the quarter-finals.

The 22-year-old next faces 2016 champion Angelique Kerber.

0030 PLAY UNDERWAY ON DAY EIGHT

Play got underway on schedule at 11 a.m. local time (0000 GMT) at Melbourne Park with Madison Keys and Caroline Garcia battling it out for a place in the quarter-finals.

The temperature was 23 degrees Celsius (73 degrees Fahrenheit) and forecast to reach a high of 26. Read our preview of the day's action here:

(Compiled by Nick Mulvenney, Aditi Prakash and Simon Jennings,; Editing by John O'Brien and Ed Osmond)