It was almost a throwaway question, but the answer was a keeper.

Elena Rybakina, the first player into Saturday’s semifinals at the Porsche Tennis Grand Prix, was asked if she had a preference for an opponent in the next match -- World No.1 Iga Swiatek or No.303 Emma Raducanu.

“I don’t have any preference,” Rybakina said, smiling a Mona Lisa smile, “to be honest.”

It might have sounded disingenuous, but Rybakina has reason to be confident against Swiatek, who went on to dismiss Raducanu in the quarterfinals. In the four matches they’ve played since Swiatek ascended to the top ranking, Rybakina has won three.

“It’s always of course tough to play against Iga, and I feel like we pushing each other ‘til the limits,” Rybakina told reporters. “Of course I want to win, but I need to be also realistic. She’s very good player on clay. She’s maybe a little bit more favorite now. But if I play well, I serve well, I move good, I have all the chances.”

The quarters were a terrific, concentrated dose of elite tennis that included the four top-ranked players in the world and all four reigning major champions. The semifinals, featuring two out of four in both categories, promise to be another day of unusual quality.

It’s No.1 Swiatek versus No.4 Rybakina and, later, No.6 Marketa Vondrousova versus unseeded Marta Kostyuk.

Let’s investigate the case for each of our semifinalists:

No.1 Swiatek vs. No.4 Rybakina, not before 2 p.m. local time

The case for Swiatek

She was pushed into a taut 70-minute opening set by Raducanu, but Swiatek displayed her bona fides in the tiebreak, winning seven of nine points. She served brilliantly, nailed a couple of swinging volleys, hit a line and was simply dominant.

The final was 7-6 (2), 6-3 and that tiebreak was an indication of how much Swiatek wants this title. She’s trying to become the first player since Maria Sharapova (2012-14) to three-peat here.

It’s been 99 weeks for Swiatek as the No.1-ranked player, and she’s used Stuttgart as a springboard to the year-end ranking the past two years, setting her course on clay. How good has she been on the dirt? Swiatek has lost three clay-court matches in the past three years. The record in that span is 39-3.

A year ago, Swiatek was coming off a rib injury when she arrived in Stuttgart. She had lost to Rybakina at Indian Wells and took more than a month off to recover.

“I wasn’t sure if I was going to be able to, without practicing really hard, to come here and play on such intensity throughout the whole tournament,” Swiatek said. “Sometimes when you’re coming back from injury you can play without any expectations, and you can feel more free.”

Make no mistake, those expectations today are very much present. How will Swiatek respond? We refer you to that first-set tiebreak against Raducanu.

The case for Rybakina

Included in Rybakina’s portfolio of victories over Swiatek, is last year’s quarterfinal on the red clay in Rome. It was 2-all in the third set when Swiatek retired with a right thigh injury. That stopped her 14-match win streak in Rome, ending the possibility of a three-peat.

As fate would have it, Swiatek is trying to win her third straight title in Stuttgart -- and Rybakina would like nothing better than to derail those plans, too.

Rybakina escapes Paolini from a break down in the third set

Rybakina put together a 6-3, 5-7, 6-3 win over Jasmine Paolini in the quarterfinals, her second consecutive match to go the distance after edging Veronika Kudermetova in the second round. Rybakina said the extended matches were normal in the transition to clay from hard courts.

“Of course, sore here and there but no issues, which I’m happy with,” she told reporters. “I know that I have quite heavy serve, but for example today in these important moments maybe didn’t help me. I was either too passive or was out like this, so I feel like I’m missing a little bit.

“It’s just part of the work. It takes time to feel better and better on clay.”

This is Rybakina’s third outing in Stuttgart -- and her first trip to the semifinals. She and Swiatek each have a tour-leading 24 wins for the year and she’s keen on being the first to 25.

No.6 Marketa Vondrousova vs. Marta Kostyuk, not before 4 p.m. local time

The case for Vondrousova

Here is why Vondrousova is always a threat:

Serving for the match at 6-5 in the third set against No.2 Aryna Sabalenka, Vondrousova lost two of the first three points. Somehow, with two crafty, lefty second serves, she regained the advantage. A backhand into the net gave Vondrousova her third career win over Sabalenka.

The current Wimbledon champion is enjoying her best effort in Stuttgart, following two Round of 16 visits.

Vondrousova, a wonderful, sometimes whimsical player to watch, outpointed Sabalenka 89-85 -- and a critical part of that was Vondrousova’s four-point margin on second serves. She also converted an astounding seven of eight break-point opportunities.

Confidence-wise, this was a big win for Vondrousova. She beat two Top 10 players on the way to the title last year at Wimbledon, including No.6 Ons Jabeur in the final. Since then, she had lost five straight matches to Top 10 players before breaking through against Sabalenka.

“I think most important thing, for my head, just to know that I can keep up with these players,” Vondrousova said. “Just play close matches with them and actually win the match.”

The case for Kostyuk

How’s this for resilience?

The 21-year-old from Ukraine saved five match points in her quarterfinal win over Zheng Qinwen. On Friday, she failed to convert her first seven match points against Coco Gauff -- and finally collected the eighth when yet another forehand found the net.

As Kostyuk approached net, there were tears in her eyes as the accomplishment began to penetrate her consciousness. She’s now beaten two Top 10 players in a row -- can she win a third?

Despite some extenuating circumstances, the answer is, without a doubt, yes.

Kostyuk outlasts Gauff in third-set tiebreak to reach Stuttgart semis

Kostyuk is feeling some wear and tear after needing three hours to defeat Laura Siegemund in the first round -- and 2 hours, 40 minutes to bring down Zheng. The match against Gauff ran another 2 hours, 48 minutes, but Kostyuk is playing with a ton of adrenaline. Plus, Vondrousova is coming off a three-set match herself.

At No.27, Kostyuk is already a formidable player, even though she’s the only non-Top 10 player left in the draw. She’s 18-6 for the year and into her third consecutive semifinal, following Indian Wells and San Diego.

Kostyuk is 0-1 against Vondrousova, a Billie Jean King Cup match last year. They were scheduled to play in the third round of this year’s BNP Paribas Open, but Vondrousova withdrew.