Serena Williams says her motivation to win major trophies remains as high as ever in motherhood after reaching the US Open quarter-finals.

Williams, whose daughter Olympia turned one on Saturday, is aiming to win a record-equalling 24th Grand Slam title in New York.

The 36-year-old American former world number one is playing her seventh tournament since giving birth.

“That desire has not gone down at all,” she said.

“And I don’t think it was capable of going up, because if it was at a 10, I was at a 15 or a 20 – and I’m still there.”

Williams, seeded 17th, has been in fine form at Flushing Meadows, dropping her first set of the tournament before recovering to win 6-0 4-6 6-3 against Estonia’s Kaia Kanepi on Sunday.

Winning the US Open for a seventh time would see her level Australian Margaret Court’s all-time record of 24 majors.

• Williams beats Kanepi to reach US Open last eight
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Williams returned to Slam competition at the French Open in May, only to withdraw before her last-16 match against Maria Sharapova of Russia because of injury.

She then reached the Wimbledon final in July but lost to Germany’s Angelique Kerber.

“My desire still remained at that incredibly high level to compete and to want to win,” Williams said.

“It would be wonderful to win a Grand Slam while having a daughter, but it’s a lot of work.

“It takes a lot of work to win those tournaments. I’m only in my third one back. I’m going to continue to grind and see what happens.”

Meanwhile, Williams says she hopes to have more children in the future – but maybe not until after she finishes playing.

“Right now is not the time,” she said. “I’m thinking about playing tennis and enjoying this time with Olympia.

“I’ll have plenty of time in the future.”

‘It was a Serena scream’

Williams cruised to the first set in 18 minutes against Kanepi, only to see the world number 44 fight back to level in the second.

The Estonian missed two break points in the first game of the third set, allowing Williams to fight back and hold serve with a backhand winner, which brought out a loud yell of “come on” from her.

“It was a Serena scream,” Williams said with a smile. “I don’t try to do it. It just comes out.

“Winning a big game and a very important game and a really tight game, I think it was just a relief.”

American 11th seed John Isner’s hopes of surpassing his best finish at a US Open could be cut short if his first baby arrives sooner than expected.

Isner reached the quarter-finals with a 3-6 6-3 6-4 3-6 6-2 win over Canadian 25th seed Milos Raonic on Sunday to equal his best showing here.

His first child is due on 22 September but he has already been thinking what would happen if there was a clash.

“I would play if it worked out I could get there and get back,” he said.

He added in comments reported on the US Open website: “If it was the day of the match, not possible. I’m not going to miss the birth, but we’ll see.”

Wimbledon semi-finalist Isner will face Juan Martin del Potro or Borna Coric next after reaching the last eight in New York for the first time since 2011.

He is the only American remaining in the men’s draw after 18th seed Jack Sock was knocked out by Georgian Nikoloz Basilashvili in the second round.

• Defending champion Nadal through
• Murray into mixed doubles quarter-finals
• Djokovic and Federer seeking last eight tie

Elsewhere, ninth seed Dominic Thiem also reached the quarter-finals by beating 2017 runner-up Kevin Anderson 7-5 6-2 7-6 (7-2) of South Africa.

The Austrian broke late in the first set and twice in the second before winning the third in a tie-break on Arthur Ashe Stadium..

It is the first time Thiem has reached the last eight in New York, and he will face 17-time Grand Slam winner and defending champion Rafael Nadal.

French Open finalist Thiem called the win “one of his best matches ever”.

Twelve months ago the 24-year-old had two match points in the fourth round against Del Potro but lost in five sets.

“It’s a dream coming true,” said Thiem. “I was really close last year, but I couldn’t close it out.”

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Former champions Novak Djokovic and Roger Federer will set up a mouth-watering US Open quarter-final if they win their matches on Monday.

Sixth seed Djokovic faces Portuguese Joao Sousa in the fourth round, while Federer plays Australian John Millman.

The former world number ones have not faced each other so early in a Grand Slam since 2007, when Federer won to reach the Australian Open last eight.

First Djokovic must beat Sousa, making his debut at this stage of a Slam.

The world number 44 has already knocked out two seeds – Frenchman Lucas Pouille in the third round and Spain’s Pablo Carreno Busta in the second.

“He’s a fighter, he’s a grinder,” Djokovic said. “He will not hand you the victory, you’ve got to earn it.”

Federer’s opponent Millman, the world number 52, is also competing in unknown territory after knocking out 14th seed Fabio Fognini in the second round.

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Sharapova enjoying the nights

Also competing on Arthur Ashe Stadium is Russian 22nd seed Maria Sharapova, who is up against Spanish 30th seed Carla Suarez Navarro in the fourth round.

The five-time Grand Slam champion is looking to extend her perfect record of 23 wins in the night session at Flushing Meadows.

The 2006 US Open winner reached the quarter-finals of the French Open earlier this year but has not gone beyond the fourth round in New York since 2012.

“It’s the energy you get, no doubt I feed off this energy,” Sharapova, 31, said.

“I don’t remember how old I was when I played my first night match, but I’m sure I was young enough to still be intimidated by the city and the lights and the atmosphere, the noise.

“But I really turned that around. I think I thrive on that. I love the atmosphere. I love that they know how to cheer hard. I thrive on playing under the lights for some reason. I love that.”

• Serena Williams reaches quarter-finals
• Defending champion Nadal into last eight
• Dominic Thiem reaches first quarter-final

Also in action…

Last year’s runner-up Madison Keys faces Slovakian 29th seed Dominika Cibulkova on Arthur Ashe before Djokovic’s match with Sousa.

Japanese 21st seed Kei Nishikori takes on German Philipp Kohlschreiber on Louis Armstrong, before compatriot Naomi Osaka faces 26th seed Aryna Sabalenka of Belarus.

And seventh seed Marin Cilic, the 2014 champion, is up against Belgian 10th seed David Goffin in the last match of the evening.

Czech eighth seed Karolina Pliskova saved eight break points to beat Ashleigh Barty in straight sets and reach the US Open quarter-finals.

The 2016 finalist broke in the opening game of the first set and the third game of the second to win 6-4 6-4.

But she withstood plenty of pressure from the Australian 18th seed.

Pliskova will face either American 23-time Grand Slam champion Serena Williams or unseeded Estonian Kaia Kanepi for a place in the last four.

“It was very tough even though the score looks easy,” Pliskova said. “I’m very happy to be through.”

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