In an Early Loss, Djokovic Battles Elbows, Errors and His Mirror Image

During the points, it was as if he were staring into a tennis mirror, as Hyeon Chung, his 21-year-old opponent from South Korea, rebooted points from extreme body positions and transformed defense into offense in ways that were eerily similar to Djokovic at his best.

“When I was young, I just tried to copy Novak because he was my idol,” Chung later explained.

His boyhood idol was not at his best in this fourth-round match in which Chung prevailed, 7-6 (4), 7-5, 7-6 (3). Djokovic’s serve, particularly his second serve, is a liability at this stage, and his baseline game is no longer rock solid.

He had 36 winners and 57 unforced errors Monday. Nine of those errors were double faults, including four straight at one early stage.

But the bigger concern is what Djokovic’s persistent right elbow pain means for his future. He took a six-month break from competition last year in an effort to heal the elbow without surgery. But in this Australian Open, his first tournament back, he was still hindered. He said after Monday’s defeat that it was unclear whether he might eventually need surgery.

“It’s frustrating of course, when you have that much time and you don’t heal properly,” Djokovic said. “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.”

When he won the French Open in 2016, Djokovic was the first man since Rod Laver in 1969 to hold all four major singles titles. During that phase, he was one of the most dominant No. 1 players — week to week — in the history of the sport.

His speed is still there. So, it appears, is his combative spirit, which explains why he decided to continue playing Monday’s match despite considerable discomfort and an injury timeout after the first set.

“I felt the pain was not that high that I need to stop the match, even though it was obviously compromising my serve,” Djokovic, 30, said of his elbow. “That, of course, is a big shot, especially against Chung, who returns well, gets a lot of balls back. I wish I could have a little bit had more free points on the first serve. But I didn’t. That’s life. I have to move on.”

He is no longer a candidate for a record seventh Australian Open men’s singles title. Instead, the quarterfinal in his section of the draw will match the unseeded Chung against the unseeded American Tennys Sandgren, whose five-set upset of No. 5 seed Dominic Thiem was arguably the bigger surprise Monday.

“I don’t know if this is a dream or not,” Sandgren said to the crowd in his on-court interview after his 6-2, 4-6, 7-6 (7-4), 6-7 (7-9), 6-3 victory. “All you guys are here, and I’m not in my underwear, so maybe it’s not a dream.”

One could understand Sandgren’s uncertainty. At 26, he has spent most of his career in tennis’s minor leagues: the satellite and challenger circuits. He had yet to win a match at a Grand Slam tournament when he arrived in Melbourne this year. (Sandgren’s given name is a family name and has nothing to do with tennis, even though he ended up excelling at it, playing at the University of Tennessee.)

But he is now in the final eight with Rafael Nadal and Roger Federer, the defending champion, who has yet to lose a set this year and defeated Marton Fucsovics, 6-4, 7-6 (7-3), 6-2, on Monday. Federer will face Tomas Berdych in the other quarterfinal in the bottom half of the men’s draw.

This article originally appeared in The New York Times.