Djokovic dropped the opening set against Zverev, one of the young guys trying to shove him aside. Djokovic trailed 3-0 in the third and 3-0 in the fourth, too, eventually even facing a set point.
Ah, but this is Djokovic we're talking about, the ultimate competitor. And this is Djokovic at the Australian Open, where no man ever has been better. So, naturally, Djokovic pulled himself together and pulled out the victory, reaching his ninth semifinal at Melbourne Park by eliminating No. 5 seed Zverev 6-7 (6), 6-2, 6-4, 7-6 (6) Tuesday night.
Djokovic appeared to be unfazed by the stomach muscle injury that he suffered in the third round. But he said he thinks there might be a correlation between issues and quarantine -- which players were forced to do after arriving in Australia.
"I don't want to sit here, complain about what we have been through, but we have to be honest and realistic that it has an effect on the physical well-being of players," he said. "Of course also mental, emotional, but physically, I mean, this is not normal."
Australia has some of the lowest COVID-19 numbers in the world yet still banned fans after a small outbreak. Fans may be allowed back in, but Djokovic wondered how countries with higher COVID-19 rates would handle tournaments.
"We have to find a way, you know, whether it's something like an NBA bubble, because I heard some players talk about that, and I don't mind to discuss about that kind of idea," he said. "Select one place and we play all the tournaments on that surface and that place. You know, three, four weeks in, three, four, two, three weeks' rest, then back again. Something like that. I don't know. On the top level.
"But we just have to discuss options, because I don't know honestly if this is going to work."
Djokovic had enough to overcome in this quarterfinal match. When things weren't going his way, he smashed a racket, sending a piece of the frame flying. Later, he plopped himself down right there at the back of the blue court, looking as forlorn as can be.
"You go through a lot of different emotions," he said. "You go through a lot of inner battle, and everyone is different. I have my own demons that I have to fight with, and I'm sure everybody else has them too. Everyone has their own way of dealing with that. To me it happens and then today it actually helped, even though I don't intentionally do it in order for it to help me.
"It's just accumulation of things that happen in big moments and some shots that were missed. I just kind of let it go. Poor racket."
Djokovic rallied, however, and is now closing in on a ninth championship in Australia, which would add to his own record for a man. It would be his 18th Grand Slam title overall, two fewer than rivals Roger Federer and Rafael Nadal (who plays in the quarterfinals Wednesday).
Both Djokovic and Zverev wore tape on their midsections to help with their abdominal issues.
That didn't stop the No. 1-ranked Djokovic from managing to produce 23 aces, including on the final point.
In the semifinals, he will face the surprise of the tournament: Aslan Karatsev, a 27-year-old from Russia who is ranked 114th and needed to go through qualifying rounds just to get into the main draw of a major for the first time.
No one ever had been to the final four in his Slam debut, until Karatsev's 2-6, 6-4, 6-1, 6-2 elimination Tuesday of No. 18 Grigor Dimitrov, who was hurt by back spasms that made tying his shoes a chore.
Zverev, the 2020 US Open runner-up and a semifinalist in Melbourne a year ago, once more had trouble against elite competition on the biggest stages. He fell to 0-8 against top-10 opponents at Grand Slam tournaments; he is 25-29 facing such foes in tour-level matches otherwise.
Information from The Associated Press was used in this report.