"The concern is huge," Vojin Velickovic, tennis editor of Serbian sports daily Sportski zurnal, told CNN. "Novak is kind of a Superman in Serbia. And Superman never loses, so you can imagine how huge this defeat was.
"People live his matches as some kind of TV series and make their daily routine according to his schedule."
Kryptonite didn't come in the form of Djokovic's fellow "Big Four" members Andy Murray, Rafael Nadal or Roger Federer in Melbourne.
Instead it was a more modest wildcard, Denis Istomin, a journeyman ranked 117th who needed to save four match points in the semifinals of the wildcard qualifying tournament against the world No. 284.
Istomin was an underwhelming 1-32 in his previous outings against top-10 opposition.
The stunning result left onlookers wondering whether Djokovic can ever regain his dominant form of 2015 and early 2016, when he claimed five majors and played in all six finals. Faster than a speeding bullet, he was making up serious ground on Federer, Nadal and Pete Sampras on the grand slam ladder.
Paul Annacone, the former coach of Federer and Sampras, doesn't expect to see another era of Djokovic dominance.
"Rarely, if ever, have we seen results that he produced in 2015 and 2016 -- and even more rare is it when an athlete regains that dominance," Annacone told CNN. "I think he can play great again and will.
"I do not think he can dominate as he did in that remarkable period of time."
If being on one of the grandest stages in tennis, Rod Laver Arena, elevated Istomin's game to new heights in their second round contest, Djokovic owned that court, winning six Australian Open titles.
But against the towering, bespectacled Uzbek -- and after eliminating the seemingly more dangerous Fernando Verdasco in the first round -- the 12-time grand slam winner blew a 2-1 lead in sets.
Explaining the defeat, Djokovic was gracious.
"He was a better player in the clutch moments," he told reporters. "He stepped it up, played aggressive. Served very well, very precise. There's not much I could do.
"Of course, I was not pleased with my performance overall."
Roland Garros hangover
Less than eight months ago Djokovic did something Federer, Nadal and Murray couldn't, winning a fourth straight major to emulate Rod Laver in 1969. The exclamation mark came at the last grand slam outside his grasp, the French Open.
A Roland Garros hangover, "private" issues that Djokovic cited but hasn't elaborated on and wrist and arm injuries have all contributed to his slide, with a split from coach Boris Becker in December another factor to consider.
While all have certainly played a part, acknowledged Djokovic, the loss to Istomin, his performance against Murray in the final of November's World Tour Finals with the year-end No. 1 ranking at stake and a third-round defeat to Sam Querrey at Wimbledon were still baffling performances.
Djokovic was crushed by Murray indoors in London, despite the Scot playing a four-hour match the day before.
He was seemingly back on track ahead of the Australian Open, ending Murray's 28-match winning streak in Doha two weeks ago; yet, unusually, Djokovic flew west back to his residence in Monte Carlo rather than east straight to Melbourne.
The now prolonged slump is something Murray, Federer and Nadal, for the most part, have all avoided or at least if they weren't related to injuries or their aftermath. Mind you, Murray was upset at the Australian Open by Mischa Zverev in the fourth round.
"Novak has just dropped a bit, and we often talk about narrow margins," said Annacone.
"We are seeing it with him. Missing targets by a few inches, a few more unforced errors, a little less of the relentless point (for point) mentality than we have seen.
"This is all natural. He has been so good for so long. Now he will have to adjust, and as great players do I would assume he will as well."
'Has to sacrifice everything'
Becker, dissecting Djokovic's reverse to Istomin, said the 29-year-old's priorities changed "after winning so much."
In December the German had revealed that Djokovic -- a father to toddler Stefan -- didn't practice enough in the final six months of 2016.
"He still loves the game very much, but after winning so much the priorities change a little bit," the six-time grand slam winner told CNN last week.
"He is now a happy family man, with a wife and a son and naturally he spends time with them."
If Djokovic wants to return to his halcyon days, Becker said tennis needs to be the top priority.
"You have to ask yourself, 'How important is this for me? How badly do I want it? And what am I willing to do to get it?' said Becker, who was alongside Djokovic for half of his grand slam titles.
"I think those are the key questions he has to ask. Obviously he has the talent and the greatness, but something that was there last year is missing, so he's got to sacrifice everything else for his next major."
'Heck of an athlete'
Becker is convinced Djokovic can rediscover his magic and he is not alone. Andre Agassi, another multiple grand slam winner, agrees.
Agassi was in more dire straits than Djokovic in the mid 1990s when a wrist injury, his disinterest with tennis and a failing marriage to actress Brooke Shields contributed to his ranking plummeting to 141st. Agassi revived his career, though, winning half of his eight grand slams after rededicating himself to tennis at the end of 1997.
"Going into 2016, I said on record I think Novak's going to win every grand slam, and everything was looking pretty darn good," Agassi said in a video call with reporters at Melbourne Park. "Then he woke up one day and it was different.
"God only knows what's going on that created that or what he's dealing with. I don't know what that is, but I know that it doesn't change overnight. If it changes that quick, it can change again.
"We all have our own unique journey. You guys had to see me hit rock bottom over the course of two years.
"I assure you, Novak won't need to learn ... in as hard of a way as I had to learn. He still has time. He's a heck of an athlete. In my opinion, one of the greats of all time. I give him a high, high chance of coming back in a hurry."
With his Australian Open ending prematurely compared to years past, Djokovic just might surface for Serbia's Davis Cup encounter against Russia at home starting February 3.
Whether it's that weekend or later, the sequel to 'Superman' Djokovic -- what comes next -- is sure to have its fair share of viewers.