Clay Court Power Rankings: Halep reigns, Swiatek, Barty make debuts

The 2021 WTA clay-court season gets underway this week at the Volvo Car Open in Charleston, South Carlina and Copa Colsanitsas in Bogota, Colombia, which means it's time to run the numbers on the Clay Court Power Rankings. 

To no surprise, World No.3 Simona Halep tops the list. The 29-year-old added two more clay titles to her resume last season, highlighted by her successful win at the Internazionali BNL d'Italia for the first time. Halep has more than a 1,500-point lead over on Madrid's defending champion, Kiki Bertens, who comes in at No.2, and more than double the points of 2020 Rome finalist, Karolina Pliskova, who sits at No.3.

Three young players are making their debuts on the Clay Court Power Rankings: World No.1 and 2019 Roland Garros champion Ashleigh Barty, 2020 Roland Garros champion Iga Swiatek and 2019 Roland Garros finalist Marketa Vondrousova. Swiatek makes her debut at No.6, Barty at No.7, and Vondrousova at No.9. 

Sloane Stephens is the lone American on the Power Rankings Top 10, boosted by her stellar run on clay during the 2018 and 2019 seasons.

The WTA Insider Clay Court Power Rankings are based on an empirical formula that isolates a player's success rate on clay courts. To measure a player's recent aptitude on the surface, the Insider team applied the following formula, which takes into account a player's results over the last five seasons:

100% of points earned on clay courts in 2020
100% of points earned on clay courts in 2019
75% of points earned on clay courts in 2018
50% of points earned on clay courts in 2017
25% of points earned on clay courts in 2016

The resulting sum accounts for a player's "Clay Court Index."

As a refresher, here's a summary of who has dominated the tour's biggest clay-court titles over that five-year span:

Roland Garros: Iga Swiatek (2020), Ashleigh Barty (2019), Simona Halep (2018), Jelena Ostapenko (2017), Garbiñe Muguruza (2016)
Mutua Madrid Open: Kiki Bertens (2019), Petra Kvitova (2018), Simona Halep (2016-2017).
Internazionali BNL d'Italia: Simona Halep (2020), Karolina Pliskova (2019), Elina Svitolina (2017-18), Serena Williams (2016).
Porsche Tennis Grand Prix: Petra Kvitova (2019), Karolina Pliskova (2018), Laura Siegemund (2017), Angelique Kerber (2016)
Volvo Car Open: Madison Keys (2019), Kiki Bertens (2018), Daria Kasatkina (2017), Sloane Stephens (2016).

Note: The Mutua Madrid Open, Porsche Tennis Grand Prix and Volvo Car Open were not played in 2020 due to the pandemic.

Here's a more detailed look at the Clay Court Power Rankings Top 10:

No.1 Simona Halep (WTA Rank: No.3)
Career Clay Court Win %: 74.3%
2019-20 Clay Court Record: 24-4
Notable recent clay court results: 2020 Rome Champion, 2020 Prague Champion, 2019 Roland Garros quarterfinalist, 2019 Madrid finalist, 2018 Roland Garros Champion, 2018 Rome finalist, 2018 Madrid quarterfinalist, 2017 Roland Garros finalist, 2017 and 2016 Madrid champion, 2017 Rome finalist.

No.2 Kiki Bertens (WTA Rank: No.10)
Career Clay Court Win %: 70.1%
2019-20 Clay Court Record: 22-8
Notable recent clay court results: 2020 Roland Garros Round of 16, 2019 Madrid champion, 2019 Rome semifinalist, 2019 Stuttgart semifinalist, 2018 Madrid finalist, 2018 Charleston champion, 2017 Gstaad champion, 2017 and 2016 Nuremberg champion, 2016 Gstaad finalist.

No.3 Karolina Pliskova (WTA Rank: No.9)
Career Clay Court Win %: 60.4%
2019-20 Clay Court Record: 13-5
Notable recent clay court results: 2020 Rome finalist, 2019 Rome Champion, 2018 Stuttgart champion, 2018 Madrid semifinalist, 2017 Roland Garros semifinalist, 2017 Rome quarterfinalist.

No.4 Elina Svitolina (WTA Rank: No.5)
Career Clay Court Win %: 65.3%
2019-20 Clay Court Record: 11-5
Notable recent clay court results: 2018 and 2017 Rome champion, 2017 Roland Garros quarterfinalist, 2017 Istanbul champion, 2016 Roland Garros Round of 16.

No.5 Petra Kvitova (WTA Rank: No.11)
Career Clay Court Win %: 68.1%
2019-20 Clay Court Record: 13-3
Notable recent clay court results: 2020 Roland Garros semifinalist, 2019 Stuttgart champion, 2018 Madrid champion, 2018 Prague champion, 2016 Stuttgart semifinalist.

No.6 Iga Swiatek (WTA Rank: No.16)
Career Clay Court Win %: 77.8%
2019-20 Clay Court Record: 14-4
Notable recent clay court results: 2020 Roland Garros champion, 2019 Roland Garros Round of 16, 2019 Lugano finalist.

No.7 Ashleigh Barty (WTA Rank: No.1)
Career Clay Court Win %: 62.9%
2019-20 Clay Court Record: 11-2
Notable recent clay court results: 2019 Roland Garros champion, 2019 Madrid quarterfinalist, 2018 Strasbourg semifinalist.

No.8 Garbiñe Muguruza (WTA Rank: No.13)
Career Clay Court Win %: 65.6%
2019-20 Clay Court Record: 11-5
Notable recent clay court results: 2018 Roland Garros semifinalist, 2016 Roland Garros champion, 2017 and 2016 Rome semifinalist, 2017 Roland Garros Round of 16. 

No.9 Marketa Vondrousova (WTA Rank: No.20)
Career Clay Court Win %: 66.7%
2019-20 Clay Court Record: 19-6
Notable recent clay court results: 2020 Rome semifinalist, 2019 Roland Garros finalist, 2019 Rome quarterfinalist, 2019 Istanbul finalist.

No.10 Sloane Stephens (WTA Rank: No.57)
Career Clay Court Win %: 59.6%
2019-20 Clay Court Record: 11-7
Notable recent clay court results: 2019 Roland Garros quarterfinalist, 2019 Madrid semifinalist, 2018 Roland Garros finalist, 2016 Charleston Champion.