Perth, Jan 3 : Alex de Minaur laid down a stunning marker for his 2024 season on Wednesday as he upset World No. 1 Novak Djokovic 6-4, 6-4 to give the host Australia a 1-0 lead in the quarterfinal against Serbia at the United Cup. De Minaur delivered a top-class all-around performance, during which he won 33 of 34 points behind first serves, to notch the biggest win of his career in 94 minutes. "It's extra special. Novak is an unbelievable competitor and what he's done for the sport is pretty special. It feels surreal, amazing, and I'm very happy to do it here in Perth and Australia. "When you go up against Novak you have to go out and enjoy it and back yourself and no matter what keep fighting until the end. Today was my day and I'm happy that I was able to get the win," De Minaur said. It was Djokovic's first defeat in Australia since he fell to Hyeon Chung in the quarter-finals at the 2018 Australian Open. The Serbian great was far below the level he showed in his season-opening victories against Zhang Zhizhen and Jiri Lehecka in Perth, and he again struggled with the right wrist issue for which he had a medical time-out against Lehecka on Tuesday. With his victory against Djokovic, De Minaur moved Australia within one win of a semi-final spot on home soil at the mixed teams event. His teammate Ajla Tomljanovic can book Australia's ticket to the last four in Sydney by beating Natalija Stevanovic in the WTA singles match next inside RAC Arena. /IANS