Sabalenka dominates but Gauff struggles on serve at WTA Finals

World number one Aryna Sabalenka and defending champion Coco Gauff experienced contrasting fortunes with their serves at the WTA Finals.

US Open champion Sabalenka hit 11 aces in a crushing 6-3 6-1 victory over Italian Jasmine Paolini in Riyadh, Saudi Arabia.

The Belarusian, who secured the year-end number one ranking earlier this week, won 66% of first-serve points and produced 24 winners to outmuscle the agile Paolini.

But French Open champion Gauff recorded 17 double faults and made 75 unforced errors as she was beaten by fellow American Jessica Pegula.

World number three Gauff had her serve broken nine times in a 6-3 6-7 (4-7) 6-2 loss to fifth-ranked Pegula in Sunday's second match in the Stefanie Graf Group.

Elena Rybakina and Iga Swiatek triumphed on the opening day in the Serena Williams Group on Saturday.

Victory over world number eight Paolini was Sabalenka's 60th win of the year and her 12th over a top-10 opponent.

She has spent 63 weeks in total at the top of the world rankings, including 55 in a row since October last year.

Sabalenka has qualified for the year-end Finals for the past five years but has never won the title. She was runner-up to Caroline Garcia in 2022.

The 29-year-old was imperious against Paolini, who is the only player competing in the singles and doubles tournaments.

The pair traded breaks in the first set before Sabalenka powered on, winning six games in a row to close out the opener and take a 4-0 lead in the second.

Paolini got on the board and took Sabalenka to deuce in the next game, but big first serves helped Sabalenka to hold, and Paolini barely threatened from there on.

"I'm getting better and better every day," said Sabalenka.

Both Pegula and Gauff struggled for consistency throughout a scrappy contest.

Pegula, runner-up in 2023, settled quicker in an opening set that began with five consecutive breaks of serve, holding for a 4-2 lead before breaking Gauff for a fourth time.

Gauff responded by breaking at the start of the second but failed to serve out the set at 5-4 when she was broken back on a double fault, and again at 6-5 after hitting three consecutive double faults.

However, she resetted admirably to take the resulting tie-break and force a deciding set.

The players again exchanged breaks of serve but Pegula would not be denied after breaking Gauff for a 3-2 lead.

Pegula reeled off five games in a row before closing out victory after two hours and 15 minutes with her second match point.

Earlier, third seeds Erin Routliffe of New Zealand and Canada's Gabriela Dabrowski began their doubles campaign with a 6-3 7-6 (7-2) win over Russians Mirra Andreeva and Diana Shnaider.

Elsewhere, Canadian 19-year-old Victoria Mboko continued her breakthrough year with a 7-5 6-7 (9-11) 6-2 victory over Spain's Cristina Bucsa to win the Hong Kong Open.

It is a second title of the season for Mboko after her stunning triumph in Montreal in August.