SYDNEY, Dec 31, 2023 (BSS/AFP) - Leylah Fernandez led Canada to a fighting victory over Chile at the United Cup on Sunday, with the former US Open finalist winning her singles rubber and then backing up in a decisive mixed doubles.

Ranked 35, she got her country off to a perfect start in their Group B tie in Sydney, cruising past Chile's Daniela Seguel 6-2, 6-3 in 73 minutes.

With Canadian number one Felix Auger-Aliassime sitting out the men's singles, 314th-ranked Steven Diez stepped up but was toppled by world number 19 Nicolas Jarry 7-5, 6-4.

It set up a deciding mixed doubles, with Fernandez teaming with Diez to battle past Seguel and Tomas Barrios Vera 7-5, 4-6, 10-8.

"I'm extremely happy with the way I played," said Fernandez, who was part of the Canadian team that won the Billie Jean King Cup for the first time this year.

The 21-year-old broke five times in her singles clash against a player in her first WTA Tour-level singles match in nearly two years, using the serve-and-volley tactic well.

"First match of the season so had some nerves, but happy with the way I was able to handle it," she said.

Diez put up a decent fight against Jarry but brief lapses at the end of each set proved his downfall.

"Steven is a grinder, a very tough player," Jarry said. "So it was a tough match for the first one of the year."

There is no night session at the mixed teams event in Sydney, given the traditional New Year's Eve fireworks.

Britain, who beat Australia to open their tournament account, took a 1-0 lead over the defending champions United States in Group C in Perth when Jessica Pegula crashed 5-7, 6-4, 6-4 to Katie Boulter.

It was Boulter's first win over a top-five player on her seventh attempt after she bounced back from a set and double-break down.

Pegula's 10th-ranked teammate Taylor Fritz takes on Cameron Norrie later.

Also in Perth, world number one Novak Djokovic will play his season opener for Serbia against China's Zhang Zhizhen, with the Chinese team on a high after beating the Czech Republic 3-0 in Group E.