Novak Djokovic was forced to dig deep to book his place in the Australian Open quarter-finals.
The men's top seed and defending champion needed four sets to beat Alexander Zverev - seeded 6th - 6-7, 6-2, 6-4, 7-6.
Djokovic's win sets up a real David v Goliath contest in the semi-finals. As the Serb chases an 18th career Grand Slam, he'll face a man with just 18-sets' worth of Grand Slam tennis under his belt.
Russian qualifier Aslan Karatsev continued his surprising run through the field in Melbourne. Grigor Dimitrov became the third seeded player to fall to the unfancied 27-year old.
Karatsev lost the first set 2-6, but left just seven more games behind him as he prevailed in four-sets.
💥 Racket smash alert 💥
Novak Djokovic taking his frustrations out on his poor tennis racket 😡#AusOpen
— Eurosport (@eurosport) February 16, 2021
"I hadn’t seen him play at all before the Australian Open," Djokovic said of his next opponent, "Of course I’ve seen him during the Australian Open.
“Very strong guy, moves well. Just has a lot of firepower from the back of the court. Great backhand, obviously from the Russian school of tennis, always great there. He serves well.
“He’s in really good form, he’s motivated and obviously has nothing to lose. I’m looking forward to it.”
Djokovic has struggled with injury throughout the tournament, and concedes preparation will be at a minimum for his clash with Karatsev.
"I haven’t been practising in the days off," said the Serb, "I’m going to keep doing the same and hopefully the result will be the same."
Whatever the result later in the week, Karatsev has already made history. He was the lowest-ranked player to make the Australian Open quarter finals in 30-years.
With his win over Dimitrov, he's become just the second ever qualifier to make the semi-finals in Melbourne, and just the fifth qualifier to reach a major men’s semifinal at a Grand Slam in the Open Era.