The tennis world awoke to a surprise on Monday, with Aryna Sabalenka replacing Iga Swiatek as No. 1 in the WTA rankings.

Sabalenka, who has won two Grand Slam titles in a sterling season, has been engaged in a battle for supremacy with Swiatek — who has a Grand Slam title of her own, and five titles in 2024 to Sabalenka’s four — all year. It was expected to run until the season-ending WTA Tour Finals in Riyadh, Saudi Arabia, next month, where Swiatek is defending champion.

Instead, Swiatek lost 120 ranking points in the latest update, and Sabalenka lost 10, leading to her leapfrogging her rival to start her ninth career week as the top-ranked women’s tennis player in the world.

But neither player took part in a tournament last week, so what happened?

Why did Swiatek and Sabalenka lose their ranking points?

Under WTA rules, players must enter and play six WTA 500-level tournaments per season. If a player is involved in fewer than that, they lose the ranking points they earned from their worst results of the season across all tournament categories as punishment — not just from the 500-level events they did play in.

The Pan Pacific Open in Tokyo is the only WTA 500 event left this season and that starts today (Monday, October 21), with Swiatek having played two 500-level events and Sabalenka four:

Neither player can now meet the mandatory figure of six, so they have begun to lose points. Swiatek’s worst result of the season to date is her fourth-round defeat to Russian world No. 28 Ekaterina Alexandrova at the Miami Open in March, which is a WTA 1000. She earned 120 points for reaching that stage of the tournament.

Sabalenka’s worst result of 2024 is her second-round defeat to Croatian world No. 19 Donna Vekic at February’s Dubai Tennis Championships, also a WTA 1000, for which she gained 10 points. Removing these points erases Swiatek’s lead over Sabalenka, and takes the latter to the summit:

Will Swiatek and Sabalenka lose further points?

Yes. Their next-worst results will be scrapped from their points totals in the next rankings update on Monday October 28, after the Pan Pacific Open concludes next Sunday October 27. Swiatek’s next worst result is her 130 points for reaching the third round of the Australian Open and Wimbledon, but her next points to drop are the 195 she earned for getting to the semifinals of the WTA 500 in Stuttgart. Sabalenka will lose 65 points, for losing in the third round of the Miami Open.

Who will be world No. 1 at the end of the year?

This will still be decided at the WTA Finals. The odds are currently in Sabalenka’s favor because of how extensively Swiatek outperformed her last year — an initially strange idea that is at the heart of the tennis ranking system.

Swiatek won the WTA Finals in 2023, winning all of her matches in straight sets and thrashing Jessica Pegula 6-1, 6-0 in the final in Cancun, Mexico, to earn 1500 points. Sabalenka lost one of her matches in the round-robin stage (to Pegula) and then lost to Swiatek in the semifinals, earning 625 points. Those points will drop off their rankings on Monday October 28.

Applying the pending point penalty, and the loss of last year’s points from the WTA Finals, Swiatek will have to surmount a deficit of 1,046 points in Riyadh to reclaim the No. 1 ranking:

Has Swiatek overhauled a rankings deficit before?

Yes, and she did it against Sabalenka, this time last year. Going into the WTA Finals, Sabalenka was world No. 1, with a lead of 630 points over Swiatek. But Swiatek then destroyed the field, dropping just 20 games in 10 sets. Pegula, who faced her in the final, was clear as to why: “She clearly really wanted that ranking,” the American told a news conference after their final. “You could tell by the way she was competing here… She was, like today, crushing people.”

After Swiatek withdrew from the WTA 1000 China Open in September (where she would have been defending champion, and so dropped 1,100 points), Sabalenka said that she hoped they would face each other again during the season in their fight to finish top of the rankings.

Aryna Sabalenka is world No. 1 for the second time in her career. (Wang He / Getty Images)

“I hope she’ll figure out the coach situation and she’ll be back in the finals in her best shape,” Sabalenka said in a news conference at the Wuhan Open, also in China. “Hopefully we can play against each other there.”

The “coach situation”, in which Swiatek parted company with Tomas Wiktorowski with whom she won four Grand Slam titles, has indeed been figured out. Swiatek has since hired Wim Fissette, who coached Naomi Osaka, Kim Clijsters and Angelique Kerber to Grand Slam titles. All three are former world No. 1s.

(Top photos: Getty Images)