PERTH, JANUARY 3

Novak Djokovic continued to struggle with his wrist injury as Australia stunned Serbia with a 3-0 win in the quarterfinals of the United Cup on Wednesday.

Poland also qualified for the semifinals with a 3-0 victory over China, while France and Greece completed sweeps of Italy and Canada respectively to progress to the quarterfinals.

Djokovic, who has had a problem with his right wrist during the tournament, found a way past Jiri Lehecka in Serbia's previous Group E match against the Czech Republic.

However, the world No. 1 struggled against Alex de Minaur as the Australian used a superb defense and a dominant serve to win 6-4, 6-4.

Djokovic was clearly in discomfort against world No. 12 De Minaur and was twice treated by the physio during the first set.

It was Djokovic's first defeat in Australia since he lost his quarterfinal at the Australian Open in 2018.

Ajla Tomljanovic followed up by giving Australia an unassailable 2-0 lead when she won 6-1, 6-1 against Natalija Stevanovic, who had stepped in for Olga Danilovic. Matthew Ebden and Storm Hunter then completed the rout by combining for a 6-3, 6-3 triumph over Serbian mixed doubles duo Dejana Radanovic and Nikola Ćaćić.

'It's extra special,' De Minaur said as Australia sealed its maiden appearance in the semifinals. '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.

'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.'

Top-ranked Iga Swiatek beat No. 14 Zheng Qinwen 6-2, 6-3 to give Poland a winning 2-0 lead after Hubert Hurkacz's 6-3, 6-4 victory over Zhang Zhizhen.

Polish pair Katarzyna Piter and Jan Zieliński sealed the sweep with a 6-3, 5-7, 10-7 win over You Xiaodi and Sun Fajing in the mixed doubles.

The Poland team will travel across Australia for Saturday's semifinals in Sydney, where they will play either France or Norway.

'I really wanted to go to Sydney especially because my coach (Tomasz Wiktorowski) told me that I can get three days off in Sydney afterwards,' the 22-year-old Swiatek said. 'So, for sure Bondi Beach is waiting for us.

'But for now we've got to focus on the semifinal and hopefully the final. I'm really happy with my game and how the atmosphere in the team is.'

Earlier in Sydney, Caroline Garcia and Adrian Mannarino led France past Italy.

Mannarino overcame Lorenzo Sonego in straight sets before Garcia beat Jasmine Paolini 6-4, 5-7, 6-4 to give France a 2-0 lead and confirm top spot in Group D.

'We have gone a step further than last year,' Garcia said. 'Obviously we're very happy with it and we want to keep going.'

French pair Elixane Lechemia and Édouard Roger-Vasselin completed the sweep with a straight- sets win in the mixed doubles.

No. 6 Stefanos Tsitsipas returned after missing Greece's opener against Chile to defeat Canada's Steven Diez 6-2, 6-3 and give his team the lead.

Maria Sakkari sealed Greece's spot in the quarterfinals when she saved four set points in the first set and then came back from 3-1 down in the second to beat Leylah Fernandez 7-6 (2), 6-3. Tsitsipas and Despina Papamichail also beat Stacey Fung and Felix Auger-Aliassime 7-5, 6-4 in the mixed doubles.