PERTH - Novak Djokovic closed out his spectacular 2023 on a winning note as the world number one eased past China's Zhang Zhizhen 6-3 6-2 on his United Cup debut on Dec 31 before doubling up to secure a 2-1 victory for Serbia in the mixed team tournament.

The 36-year-old showed no signs of slowing down as he lifted the Australian, French and US Open trophies last season - with his only blip being a five-set defeat in the Wimbledon final - before securing the year-end top spot at the ATP Finals.

Djokovic wasted little time in priming himself for a tilt at a record-extending 11th trophy at the Jan 14-28 Australian Open as he dismantled world number 58 Zhang in 72 minutes at a packed RAC Arena in his first match of the 2024 season.

Zheng Qinwen rolled over Olga Danilovic 6-4 6-2 to make it 1-1 but Djokovic returned to partner Danilovic and seal a 6-4 1-6 10-6 victory against Zheng and Zhang.

Taylor Fritz and Jessica Pegula combined to help defending champions the United States beat Britain 2-1 in Group C as they overcame Neal Skupski and Katie Boulter 1-6 7-6(4) 10-7.

The Americans can book their place in the quarter-finals of the US$10 million (S$13.21 million) team event that features 18 countries with a win over Australia on Jan 1.

Boulter continued her strong start to the season after an opening win over Australia's Ajla Tomljanovic as she clawed her way back from a set and 3-0 down to quell world number five Pegula 5-7 6-4 6-4 and put Britain up 1-0.

Fritz dragged his team into contention as he managed a left thigh problem to beat Cameron Norrie 7-6(5) 6-4.

In the only match in Sydney, Canada earned a 2-1 win over Group B opponents Chile with Steven Diez and Leylah Fernandez beating Tomas Barrios Vera and Daniela Seguel 7-5 4-6 10-8.

Fernandez subdued Seguel 6-2 6-3 in the tie's opener before Nicolas Jarry won 7-5 6-4 against Diez, who had stepped in for Canadian number one Felix Auger-Aliassime. REUTERS