Coco Gauff keeps her US Open title defence alive

Coco Gauff has turned things around after being a set down to beat Elina Svitolina in the US Open's third round, extending the 20-year-old American's defence of her first grand slam title.

Gauff made mistake after mistake in the first set at Arthur Ashe Stadium and dropped its last 11 points against the 27th-seeded Svitolina, a three-time major semi-finalist.

"She's a fighter," Gauff said after winning 6-3 3-6 6-3 .

"I knew I had to play my best."

But Gauff managed to reel off nine of 11 games in one stretch and won despite losing the opening set, something she did three times en route to winning the 2023 trophy, including in the final against Aryna Sabalenka.

The secret this time?

"I tried to be more aggressive on my forehand side," Gauff said, "and tried to make less errors on the backhand."

The comeback ends a five-match losing streak for Gauff against opponents ranked in the top 50 and might be just what she needs to move past a recent slump that saw her win just five of her previous nine matches.

On Sunday, Gauff will face No.13 Emma Navarro, one of her teammates at the Paris Olympics and who also beat her in Wimbledon's fourth round.

Navarro advanced with a 6-4 4-6 6-3 victory over No.19 Marta Kostyuk.

Joining Gauff in the fourth round is the woman she conquered in last year's decider - Aryna Sabalenka.

The Belarusian finally got rolling after a poor first set in the latest-starting match in US Open history, regrouping to beat No.29 Ekaterina Alexandrova 2-6, 6-1, 6-2.

The No. 2 seed didn't get underway until 12:07am and had dropped the first set barely a half-hour later. But she seized control early in the second set, winning 10 straight games to open a 5-0 lead in the third.

The American women's cohort got a bit smaller when 2017 finalist Madison Keys lost a tightly fought contest against Belgian Elise Mertens 6-7 (7-5) 7-5 6-4.

Keys, who reached the semi-finals a year ago, started strong but could not break through Mertens' defences in the end as she was unable to convert five break point chances in the final set.

Mertens will now meet Sabalenka for a spot in the last eight.

Victoria Azarenka saw her 17th attempt at winning the Open come to a disappointing end as unseeded Wang Yafan downed the veteran 20th seed 6-4 3-6 6-1.

A polished Wang bested the two-time major winner and Belarusian former world No.1 in lengthy exchanges to extend her deepest ever run at a grand slam.

Azarenka, a three-time US Open runner-up, committed 32 unforced errors and dropped serve six times in the two hour 22 minute battle.

Wang will meet Paul Badosa in the round of 16, the Spaniard saving a match point in a 6-4 1-6 7-6 (10-8) win over unfancied Romanian Gabriela Ruse.

Australian Open runner-up Zheng Qinwen took down unseeded German Jule Niemeier 6-2 6-1 to also reach the fourth round.

The Olympic gold medallist and seventh seed fired off eight aces and seized five break points on the Grandstand hard court in her first straight-sets victory of the year's final major.

"Finally, it's the first match I won in two sets ... It's not (been) easy for me to play after Olympic Games," said Zheng, who has noted previous struggles with focus after deep tournament runs.

Zheng will meet Croatian Donna Vekic, whom she beat in the Olympic final earlier this month, in the fourth round.

Vekic, who beat American Peyton Stearns 7-5 6-4, said she was optimistic she would do better against Zheng on New York's hardcourts rather than on clay at Paris.