Reilly Opelka hammered 16 aces and defeated top-seeded Novak Djokovic 7-6 (6), 6-3 in the quarterfinals of the Brisbane International in Australia on Friday.

Ranked No. 293 in the world, Opelka scored points on 80 percent of his serves against the Serbian legend. In February 2022, he was ranked No. 17 before hip surgery sidelined him.

Next up for Opelka is Giovanni Mpetshi Perricard of France, who eliminated Czech Jakub Mensik 7-5, 7-6 (5).

The other semifinal will pit Czech Jiri Lehecka against Grigor Dimitrov of Bulgaria. Lehecka topped Chile’s Nicolas Jarry 6-4, 6-4, and Dimitrov’s match against Jordan Thompson was cut short when the Australian retired with Dimitrov up 6-1, 2-1.

United Cup

Czechs Tomas Machac and Karolina Muchova swept the Italian duo of Flavio Cobolli and Jasmine Paolini to advance to the semifinals of the United Cup in Australia.

Machac needed just 54 minutes for his 6-1, 6-2 win, while Muchova was a 6-2, 6-2 victor over Paolini.

Machac and Muchova, seeded eighth in the mixed-team event, will be in action again Saturday in a semifinal match against the top-seeded American duo of Taylor Fritz and Coco Gauff.

In the other semifinal, second-seeded Poland will take on Kazakhstan, the ninth seed

Hong Kong Open

Jaume Munar and Alexandre Muller set up a semifinal clash after upsetting seeded opponents.

Munar, of Spain, eliminated second-seeded Lorenzo Musetti of Italy 2-6, 7-6 (4), 7-5, while Muller defeated fellow Frenchman Arthur Fils, the fourth seed, 3-6, 6-3, 6-1.

The other semifinal will feature Kei Nishikori of Japan and China’s Juncheng Shang, who also needed three sets to advance.

Nishikori bested Cameron Norrie of Great Britain 6-3, 3-6, 6-2. Shang came from behind to beat Fabian Marozsan of Hungary 1-6, 6-3, 6-4.

–Field Level Media