RIYADH, Saudi Arabia — Dominika Cibulkova had to really grind to qualify for the 2016 WTA Finals in Singapore.

After reaching the Wuhan final, she took a late wild-card into Linz — defeating Viktorija Golubic in the final and vaulting into the year-end championship with the very best players in the world.

And that was by far the easiest part.

“When we arrived to Singapore, I started to feel this pressure,” Cibulkova said recently from her home in Bratislava, Slovenia. “Like, `OK, this is my first time here. I don’t want to look like I don’t belong.’”

And then the fiery 5-foot-3 player lost her first two group matches, to World No.1 Angelique Kerber and Madison Keys.

“I was playing so stressed [against Kerber] I made myself tired,” Cibulkova said. “I was cramping second set. I never beat Keys before. I couldn’t read her serve.”

Afterward, Cibulkova’s coach, Matej Liptak, told her she still had a slight chance to get through to the semifinals. All she had to do was beat an in-her-prime Simona Halep in straight sets, while Kerber did the same to Keys.

And it went down precisely that way. Incredibly, Cibulkova would sweep through the semifinals (defeating Svetlana Kuznetsova) and Kerber in the final, capturing her biggest title.

“I never won a Grand Slam in my career, so this is for me, I won the championships,” she said. “It was huge.”

Eight years later, now retired and a mother of two, Cibulkova remembers that run in exquisite detail, even specific points. And well she should, for she and Agnieszka Radwanska, in back-to-back years, are the only two women to lose two group matches and go on to win the WTA Finals title.

There have been only eight occasions where a player lost twice and progressed to the semifinals or better: 2003: Amelie Mauresmo, 2009: Venus Williams, 2011: Vera Zvonareva, 2013: Jelena Jankovic, 2014: Radwanska, 2015: Radwanska, 2015 Petra Kvitova, 2016: Cibulkova.

We bring this up because the WTA Finals Riyadh presented by PIF is at a critical juncture. As of Wednesday, there are still four players with a chance to advance to two semifinal spots. Yes, group play is a fun — and forgiving — format.

The Purple Group semifinalists will be World No.1 Aryna Sabalenka and the winner of Wednesday’s match between Jasmine Paolini and Zheng Qinwen.

The Orange Group scenarios are vastly more complex. On Thursday, Barbora Krejcikova and Iga Swiatek will play for the second semifinal spot. The complication? They won’t be playing each other. Krejcikova meets Coco Gauff, while Swiatek gets Jessica Pegula. 

It might take a Nobel prize-winning mathematician to unravel the permutations.

Of the five possible outcomes, only one sends Swiatek to the semifinals — but based strictly on the seeds, it is the most likely. Quite simply, Swiatek needs to defeat Pegula while Gauff beats Krejcikova.

If Krejcikova wins, she’s in. There’s even a scenario (Gauff and Pegula both win) that advances Krejcikova with a 1-2 record.

After losing her opening match to Sabalenka, Zheng reflected on the unusual nature of group play.

“Usually, when I lose a match, I feel sad because you are allowed to get sad because you have time,” Zheng said. “But after I lost this match, I didn’t feel sad. I just feel what I have to do better for trying to get the next match. 

“If I feel sad is a lose energy in this tournament, because you still have many matches to go.”

When every match counts, anything can happen

Eighteen-time Grand Slam singles champion Martina Navratilova has vast experience at the year-end championships. She was an eight-time winner in singles and 13-time champion in doubles.

“You understand the format going in,” Navratilova said recently. “If you win all three, no worries. But if it’s 2-1 or 1-2, you still have a chance. It might come down to how many sets you lost. 

“Stakes mean more, while meaning less. Meaning you can have a losing record and get through. And you can have a winning record and not get through. It’s kind of crazy. Everybody you’re playing is Top 10 in the world, so you better be ready to go for it.”

WTA Finals Riyadh tournament director Garbiñe Muguruza, the winner three years ago in Guadalajara, lost her third group match that year but still advanced to the semifinals.

“Strange,” Muguruza said of the group-play vibe. “It gives you a little bit of a chance if things don’t go well right away. When you think about it, every match could be a Grand Slam final. So maybe the first match you’re not feeling great. You have a tough opponent, but you still have hope.

“I’m OK with it because it’s the only tournament we have with this format.”

Caroline Garcia, the No.6 seed two years ago in Fort Worth, defeated Coco Gauff in her first group match, then lost to top seed Iga Swiatek in the second. To reach the semifinals, she needed to pull out a third-set tiebreak against Daria Kasatkina.

“In Fort Worth, it came down to the winner of me and Kasatkina — loser goes home,” Garcia said. “This match had very spicy emotions, was such a roller coaster match and so, so long.”

Garcia claimed the final spot by winning the third-set tiebreak 7-6 (5) — a frame that required 80 minutes.

With that help from Kerber, Cibulkova made the 2016 semifinals despite winning three sets and losing four.

“I think this can be hard for Angelique,” Liptak told her. “Because she got you into the semifinals. I think she made a big mistake.”

After losing six of the first seven games to Kuznetsova, Cibulkova survived a second-set tiebreak and advanced to meet Kerber in the final. The final was 6-3, 6-4 for Cibulkova.

“When I get to the match point, OK, my feet started to shake,” Cibulkova said. “I was like, ‘I cannot do this. It was the most scary moment of my life.’

“I say to myself, `It’s now or never, or you will regret this moment until the end of your life. You have to do it.’ And I did. This was the best moment of my career. I can’t beat that, ever.”

The year before, Radwanska completed a similarly wild journey through the WTA Finals’ Singapore draw. 

Like Cibulkova, she finished the regular season with a flurry in Asia that culminated with a title in Tianjin. Radwanska qualified No.5, but the gap between No.4 Petra Kvitova and No.8 Lucie Safarova was a mere 270 points. 

Radwanska lost her first two group matches, to Maria Sharapova and Flavia Pennetta, and faced long odds to reach the semifinals. She needed to beat Halep in straight sets and have Maria Sharapova do the same to Flavia Pennetta.

Radwanska did her part with a 7-6 (5), 6-1 defeat of Halep. She was undergoing physio treatment in her hotel room when they turned on the television.

“Suddenly, it was going the wrong way for me,” Radwanska said. “I think it was 4-1 and two breaks up [for Pennetta] — so we turned it off.

“In my head, I was packing, scheduling my offseason. One step I was already at home. Then I looked at the live score and it was 4-all. She was coming back, so we turned on the TV again. Couldn’t believe she won that thing in two sets and I was in.”

And then, very nearly, out. After dropping a first-set tiebreak against Muguruza, Radwanska escaped with a 6-7 (5), 6-3, 7-5 win, calling it one of her best ever.

The final, a 6-2, 4-6, 6-3 victory over Petra Kvitova, was another tight one.

“Actually, I don’t really know how I did it,” Radwanska said. “In the last game, I was looking at my shoes — not the crowd, the score, the lights, anything. I was shaking in the end.

“That’s history, winning that title. In tennis, especially at the year-end championships, you never really know what’s going to happen.”