Djokovic fearing new injury lay-off
Novak Djokovic, the six-time winner of the Australian Open, admitted that he had no idea when he would play again after being eliminated from this year's tournament by world No 58 Hyeon Chung.
Djokovic took a medical timeout in the first set to have treatment on his troublesome right elbow.
The Serb was able to compete wholeheartedly during this 3hr 21min war of attrition, but he confirmed afterwards that the injury remained a serious issue despite the 22-week break he took after last year's Wimbledon.
"It's frustrating, of course, when you have that much time and you don't heal properly," said Djokovic.
"But it is what it is. There is some kind of a reason behind all of this. I'm just trying my best, obviously, because I love this sport.
"I enjoy training (and) hoping that I can get better, perform and compete. Today was one of those days where, unfortunately, it was too much to deal with."
Asked whether he needed another long break to give the elbow time to heal, Djokovic added: "I really don't know. I have to re-assess everything with my medical team, coaches and everybody. Scan it, see what the situation is like.
"Last couple weeks, I played a lot of tennis. Let's see what's happening inside."
Djokovic's usually fierce serve was most obviously affected. He hit only two aces, while his regular double-faults helped Chung race to a 4-0 first-set lead.
Djokovic said that the level of pain was not high enough to make him consider a retirement, and that he was hoping to extend the contest into a fourth set to test the South Korean's inexperience in lengthy matches.
But Chung hung tough during the pressure moments of his 7-6, 7-5, 7-6 victory to earn a very winnable quarter-final against Tennys Sandgren of the USA - probably the most unlikely player to reach the last eight of a men's Slam in 15 years.
Despite his physical handicap, Djokovic was still operating at a high level, and this win was no freebie for Chung, the 21-year-old who won last year's ATP NextGen Finals in Milan.
To cross the line, he needed not only freakish mobility and endurance but a cool head in the closing stages.
Remarkably, this was the first straight-sets defeat that Djokovic had suffered at the Australian Open since 2007, when he was 19 and lost to Roger Federer in the fourth round.
Chung plays a similar form of tennis to Djokovic - relentless weight and accuracy from the back of the court, combined with a physical flexibility that helps him chip the ball back from the most desperate positions.
"It's a dream come true," said Chung, who failed to win a set when he played Djokovic here in the first round two years ago.
"When I was young, I was just trying to copy Novak because he is my idol. I'm just honoured to play him again."
The quality of Chung's play was commended by the watching Jamie Murray, who wrote on Twitter, "That was the most Novak-esque performance I've seen - and it was by Chung!
"It's to do with Chung's movement and ability to hit amazing shots from defensive positions especially out of his backhand corner - just like Novak has done for the past however many years."
Even Djokovic had to admit that he was beaten at his own game. "You know, we do play very similar. He definitely has the game to be a top-10 player, without a doubt.
"How far he can go, that depends on him. Obviously, I respect him a lot because he's a hard worker, he's disciplined, he's a nice guy, he's quiet.
"You can see that he cares about his career and his performances. I'm sure that he's going to get some really good results in the future."
Chung's nickname on Tour is 'The Professor' on account of his glasses, which are rare in this sport.
He has high-level astigmatism, which cannot be corrected by contact lenses. And, in fact, it was his eyesight that was responsible for his sporting career in the first place.
As a seven-year-old who was struggling to read the blackboard at school, he was taken to the optician, who recommended that he focus on the colour green.
Tennis balls, which are best described as a garish fluorescent yellow, came near enough.
Roger Federer continued his run of straight-sets wins as he disposed of Marton Fucsovics 6-4, 7-6, 6-2.
He will face Tomas Berdych in his quarter-final tomorrow, a repeat of the third-round meeting last year that saw Federer rediscover his best form after a six-month lay-off.
© Daily Telegraph, London