Top seed Novak Djokovic crashed out of the Brisbane International in a straight-set quarter-final defeat by Reilly Opelka.

Djokovic, chasing his 100th ATP title, went neck-and-neck with the American in the first set before Opelka eased to a 7-6 (8-6) 6-3 victory in one hour and 40 minutes.

Opelka, 27, will now face France’s Giovanni Mpetshi Perricard, who beat Jakub Mensik 7-5 7-6 (7-5) to reach the semi-finals.

“[Djokovic] is the greatest tennis player ever. But it’s difficult being in his position,” said Opelka, who is ranked 293rd in the world.

“The reality is we have nothing to lose against him, so you end up playing more freely and taking a lot more risks because it’s your only chance. If you play your normal level, he wins every time.”

Opelka, who was sidelined for almost two years since 2022 after undergoing hip and wrist surgeries, is looking to win his fifth career title in Brisbane.

“It was tough. There were a lot of uncertainties and doubt,” added Opelka.

“I watched a lot of my friends on TV which was fun, motivating and kept me interested in the sport. I also watched Novak become the greatest during that period.”

Meanwhile, 24-time Grand Slam winner Djokovic will shift his focus to winning a 11th Australian Open (12-26 January) title under his new coach Andy Murray.

In the other Brisbane semi-final, defending champion Grigor Dimitrov, who received a walkover after Jordan Thompson retired hurt, will face Jiri Lehecka, who beat Nicolas Jarry 6-4 6-4.