We're down to the final four at the Dongfeng • Voyah Wuhan Open, and opportunity abounds for a frequent WTA 1000 champion and three players looking for their first title at that level.

The first semifinal pits a resurgent Sonay Kartal against Jelena Ostapenko, who returns to this stage in Wuhan after nearly a decade.

And in the second semifinal, the first all-Polish WTA Tour semifinal in the Open Era, Iga Swiatek will play Maja Chwalinska.

Here's what to watch for in the two intriguing matches on Saturday.

After a season-long race, the world's top players converge in the California desert with the WTA's biggest title still to be won.

[7] Iga Swiatek vs. [16] Maja Chwalinska

Swiatek leads the head-to-head 1-0

This is a special one. Though Swiatek and Chwalinska have never played at the WTA Tour Driven by Mercedes-Benz level, they have a storied history and go way back. They were doubles partners as juniors, reaching the Australian Open girls' doubles final in 2017. The year prior, they played their lone professional singles match at an ITF tournament in Stockholm, in just the second pro tournament of Swiatek's career. They were both just 15. Swiatek won that match 6-2, 6-3.

Fast forward a decade later, and Swiatek is a six-time Grand Slam champion and former World No. 1. Chwalinska, meanwhile, emerged this past summer with a stunning run to the Roland Garros final, and she's built on that result during the Asian Swing. The World No. 22 is into her second semifinal in as many months, and third overall, and will make her Top 20 debut on Monday regardless of the result against Swiatek.

Swiatek's path to the semifinals has been smooth, with straight-set wins over Magdalena Frech, Ashlyn Krueger and Ann Li. It's been less straightforward for Chwalinska, whose four wins included an upset of 10th-seeded Iva Jovic, the biggest win of her career by ranking. Her stiffest test of the week came from Maria Sakkari, who pushed her to the brink in a 6-0, 3-6, 7-5 win for Chwalinska on Friday. 

Chwalinska crucially saved four of her five break points in that match, and consistently put pressure on Sakkari's serve, converting four of 15 break-point opportunities. Throughout the Asian Swing, and again on Friday, she has demonstrated that her creative, varied approach is effective off the clay.

It will surely be a tale of contrasting styles, but these players know what to expect from each other. And though the stakes are high, with a WTA 1000 final berth on the line, both are appreciative of the full-circle moment.

"I feel like I know her forever," Chwalinska told reporters, prior to knowing if she would play Swiatek or Li. "Because basically we started playing tournaments together. It would be amazing, really. I think it would be great for us, and great for Polish tennis, as well.

"It would be a great honor for me also, because she's such a great champion. She's done almost everything in our sport, so it would be a great privilege to play."

Sonay Kartal vs. Jelena Ostapenko

Head-to-head tied at 1-1

The dream week, and the dream comeback, continues for Kartal, who is playing just her third tournament after six months on the sidelines. The World No. 170 is into her first career WTA 1000 semifinal, and just the second semifinal of her career, following upset wins over ninth-seeded Belinda Bencic, 15th-seeded Jasmine Paolini and fifth-seeded Elina Svitolina, the highest-seeded player left in the draw.

Svitolina was the toughest test for Kartal. In a match that went down to the wire, the 24-year-old Brit earned her first break point of the third set on match point, at 5-4, and converted it when Svitolina's forehand sailed long. It was just the second Top 10 win of her career.

Kartal is now a perfect 12-0 this season when she takes the opening set.

"I think these courts help my game out massively," she told reporters on Friday. "I think, despite being out for so long, I came into these events knowing how much I like the atmosphere here and the environment and the surface. So I think that definitely helps, for sure.

"...I'm playing with so much confidence now. I'm playing with more confidence than when I started the year, before this injury."

Ostapenko is also playing with tremendous confidence, evidenced by her aggressive shot-making. The World No. 34, who returns to the semis in Wuhan for the first time in nine years, has hit 138 winners through four matches, the most of any player in the tournament. Following back-to-back three-set wins over Jessica Pegula and Leylah Fernandez, Ostapenko got past 11th-seeded Diana Shnaider in straights on Friday, though she did save a pair of set points in the first set. She was overpowering yet again in that match, adding 32 winners to her tally.

Ostapenko has made three WTA 1000 titles in her career, and is looking to win her first at that level.

Kartal and Ostapenko split their two career meetings last year, though both were on grass. Kartal hopes that the hard courts will change the equation.

"She hits a great big ball on a grass court," Kartal said, "so I'm hoping this court can slow down a little bit for me. But again, I know I'm in for a good battle."