Novak Djokovic’s competitive preparation for the Australian Open came to a premature end on Friday.

Reilly Opelka, the American world No. 293 who returned to tennis after injury in July last year, produced a display of clinical serving and measured aggression from the ground to beat Djokovic 7-6(6), 6-3 in the Brisbane International quarterfinals.

Djokovic did not create a break point on the American’s serve in the first set, but fended off three against him by manoeuvring Opelka from side to side. He repeated the trick in the tiebreak, pulling back a 2-4 deficit to 6-6, but as he had done all set, Opelka — once ranked world No. 17 — leaned into his forehand at the opportune moment to draw a floating ball that he put away with a smash. An ace sealed the set.

Djokovic finally created a break point in Opelka’s second service game of the second set, but the latter snuffed it out with a rapid serve out wide and won the game with a thumped pass that Djokovic could only volley wide.

Opelka broke in the very next game, taking his chance on break point as the duo traded groundstrokes bang on to the baseline before the American cannoned an inside-out forehand into an off-balance Djokovic’s backhand corner. Opelka eased through the rest of the match to see out the victory, and will face fellow huge-server Giovanni Mpetshi Perricard in the semifinals.

Djokovic, who will link up with new coach Andy Murray ahead of the Australian Open, appeared irritated by heavy and humid conditions in Brisbane, frequently staring at his hands in disbelief and blowing on them constantly between points in the tight parts of the first set.

Overall though this shouldn’t be a loss that will worry him unduly, with the story of the match really being the sensational level that Opelka was able to produce. Against such a fearsome server this kind of display is always a risk, much more so over best of three sets rather than best of five at the slams, which is absolutely Djokovic’s priority right now. He would have liked another match or two, but knows his body well enough to ensure he isn’t undercooked going into the first Grand Slam of the year, and an event he has won a record 10 times.

Elsewhere on Friday, the Czech Republic ended Italy’s bid to win a third straight team competition with a convincing 2-0 win in Sydney to reach the United Cup semifinals. The Czechs won both matches comfortably in straight sets, with Tomas Machac thrashing Flavio Cobolli 6-1, 6-2 in less than an hour after Karolina Muchova made a statement ahead of the Australian Open by defeating the world No. 5 Jasmine Paolini 6-2, 6-2. The Czech Republic will face the United States in the semis on Saturday, with the winners facing either Poland or Kazakhstan in the final.

Meanwhile there were wins in Brisbane and Auckland for present and former world No. 1s Aryna Sabalenka and Naomi Osaka respectively — the latter reaching her first semifinal since 2022 with a three-set win over the American Hailey Baptiste. Sabalenka, a two-time defending Australian Open champion, eased into the Brisbane semis with a 6-3, 6-4 win over Marie Bouzkova. In the men’s Brisbane event, the other semifinal will take place between Grigor Dimitrov and Jiri Lehecka after they beat Jordan Thompson and Nicolas Jarry respectively on Friday. 

Over in Hong Kong, China’s Shang Juncheng continued his impressive form with a three-set win over Fabian Marozsan to reach the semifinals. He’ll play either Cameron Norrie or Kei Nishikori next.

The Australian Open begins on Sunday January 12, with further warm-up events next week (though not ones that Djokovic is scheduled to be taking part in).