It began with 128 contenders, but now the women's draw at the US Open is down to just four.

After almost two weeks of grueling action in the searing heat in New York, the semifinalists have been confirmed for the fourth and final grand slam of 2023.

American teenager Coco Gauff faces Czech world No. 10 Karolína Muchová, while world No. 2 Aryna Sabalenka takes on local favorite Madison Keys.

Here's everything you need to know ahead of the US Open women's semifinals.

How to watch

Gauff and Muchová kick off proceedings in Arthur Ashe Stadium at 7 p.m. ET on Thursday, with Keys and Sabalenka following them.

Viewers in the US can watch all the action on ESPN, while Sky Sports will broadcast the matches in the UK.

Gauff vs. Muchová

For those eagle-eyed fans, you might remember this specific match-up taking place very recently.

The two took to the court just under three weeks ago in the final of the Western & Southern Open in Cincinnati, with Gauff winning in straight sets to claim to biggest title of her career.

Her victory in Ohio came in the midst of Gauff's best period of form in her blossoming tennis career, momentum she's continued into the US Open.

The American's most recent outing at Flushing Meadows was another impressive performance, beating Jelena Ostapenko with ease for her 10th victory in a row.

It has been somewhat of a coming-of-age tournament for Gauff, who looks like a serious contender to win her maiden grand slam title, but she insists she's not getting ahead of herself.

"There's still a lot of tennis left to play," Gauff said. "I'm still in the mindset that I'm in the beginning of the tournament. Before I would think close to the end, but right now, I have the mentality that I told myself I still have another two weeks to play.

"Right now, I feel emotionally fresh, which I think was the problem in the past in grand slams. I would emotionally be drained."

Muchová is very much seen as the underdog against Gauff, despite also showing excellent form recently to rise up to a career-high ranking of No. 10 in the world.

The Czech, who lost in the final of the French Open earlier in the year, has only dropped one set en route to the semifinal as she continues an extraordinary comeback season after suffering a series of injuries last year which threatened her career.

"Mental strength ... how would I describe it?" Muchová asked. "I always feel that I'm a pretty tough cookie in life. That helps with tennis. But yeah, some days are better; some days not.

She added: "I don't really want to say all the keys with the tactics. So I'll just focus on myself. She's very athletic. She never gives up. Runs for every ball. Doesn't do many mistakes. She has all the strokes."

Keys vs. Sabalenka

The second semifinal of the day will also see an American with the crowd behind her taking on a European as Keys faces Belarus' Sabalenka.

No. 17 seed Keys is enjoying a revival at the tournament, having lost in the final to Sloane Stephens in 2017.

She has already beaten three seeded players on her way to the semifinals, most recently blitzing past Wimbledon champion Markéta Vondroušová in the quarterfinals as she continues to draw on the home crowds to inspire her victories.

"I think I have had just a really good mindset going into the matches. I've been trying to be maybe just a little bit more emotionally balanced," Keys said on her US Open success after her victory over Vondroušová.

It was her 26th career victory over a top-10 player and sets up a heavyweight clash against Sabalenka, who is currently the in-form player in women's tennis having not dropped a set on her path to the semifinals.

The Belarussian eased past Zheng Qinwen in the quarterfinals to reach her fifth consecutive grand slam semifinal and continue her remarkable record in major quarterfinals -- she has now won her first seven grand slam quarterfinal matches, second on the all-time list behind Chris Evert who, amazingly, won her first 48.

The 25-year-old will be crowned as the new world No. 1 when the new rankings are released on Monday and, after claiming her first grand slam title at the Australian Open earlier in the year, Sabalenka is the favorite to win her second of the year.

She's the first woman to reach the semifinals at all four grand slams in a year since Serena Williams in 2016 and says she has learned a lot from her prior results.

"I had a couple of really tough losses this year," Sabalenka said. "But as I said, we're not losing, we're learning. I'm just getting more experience and getting stronger."