'No, I don't have a butler' - the billionaires' daughters chasing US Open

Aryna Sabalenka has been tipped as the one to beat at this year's US Open since she arrived in New York.

The Belarusian world number two is the highest-ranked player left in this year's draw as she looks to add to her two Australian Open titles.

A runner-up at Flushing Meadows last year, Sabalenka will face American Emma Navarro in the last four on Thursday.

That will be followed by another home hope, Jessica Pegula, against Karolina Muchova.

BBC Sport looks at the form and the stories of the four semi-finalists.

Head-to-head: 1-1 Last meeting: French Open fourth round, Sabalenka won 6-2 6-3

Even with world number one Iga Swiatek in the draw, Sabalenka's hard-hitting game has made her the one to beat on the hard courts.

Sabalenka retained her Australian Open title in January in emphatic fashion, storming to the trophy without dropping a set.

However, in March her former boyfriend, Konstantin Koltsov, died in what she called "an unthinkable tragedy".

Sabalenka continued playing - something she said, with hindsight, she should not have done - before she struggled with a stomach problem in her French Open quarter-final loss and a shoulder injury ruled her out of Wimbledon.

However, she claimed her first title since Melbourne in Cincinnati in the build-up to the US Open, and the fast New York courts suit her huge serve and devastating forehand.

Sabalenka on Navarro: "Beautiful to see - she's working hard, playing really great tennis, smart tennis, moving well, hitting pretty heavy shots."

Navarro beat second seed Sabalenka on the Indian Wells hard courts in March for the biggest win of her career by ranking.

The American has been one of the stars of the year, winning her first WTA title in Hobart in January, before consistently improving on her Grand Slam showings.

She reached the Australian Open third round, the fourth round at Roland Garros, made a quarter-final showing at Wimbledon before reaching the last four in New York.

She has also had some statement wins, including beating Coco Gauff at both Wimbledon and the US Open, ending her compatriot's title defence at the latter.

The daughter of a billionaire businessman, Navarro is a highly intelligent player who use slices and drop shots to mix up the pace of rallies.

Navarro on her mentality: “I always step on the court believing that I have a chance to win, and it's always my priority to just put my best foot forward."

Head-to-head: Pegula leads 1-0 Last meeting: Cincinnati Open second round, Pegula won 5-7 6-4 6-2

It is a long-awaited first Grand Slam semi-final for Pegula, who lost her previous six quarter-finals.

She split with long-term coach David Witt after the Australian Open, where she lost in the second round, before her clay season was interrupted by neck and back injuries.

A second-round Wimbledon exit was followed up by a superb run, with Pegula defending her Canadian Open title before reaching the Cincinnati final a week later.

Although she lost the Cincinnati showpiece to Sabalenka, she has been in superb form at her home Slam, having reached the last four without dropping a set.

Born in Buffalo, New York, Pegula's parents own the Buffalo Bills, who play in the NFL, and they supported her through her junior years as she struggled with injuries.

She claimed a stunning win over Swiatek in the quarter-finals, barely letting up in intensity and returning serve solidly to end her last four hoodoo.

Pegula on Muchova: "She's so good, so talented, so athletic. I love how she just doesn't play and comes back and beats everybody. I'm gonna have to bring my best tennis."

Muchova has played just six tournaments since last year's US Open, having only returned to the WTA Tour in June following wrist surgery.

Despite the relative lack of playing time, Muchova has yet to drop a set in New York, and has seen off some big names.

She beat four-time Grand Slam champion Naomi Osaka in the second round and fifth seed Jasmine Paolini in the fourth round, before overcoming an apparent stomach illness in her quarter-final win over Brazil's 22nd seed Beatriz Haddad Maia.

The Czech was runner-up to Swiatek at the French Open in 2023, and is the only player to have taken a set off the world number one in a Roland Garros final in four attempts.

A crafty player, Muchova has been compared to both Justine Henin and Roger Federer for her adeptness around the court.

Muchova on her wrist surgery: "This last injury was one of the worst ones that I had. Now looking back, I'm like, oh, it actually flew by and I feel strong again.'"