With her Volvo Car Open title, Madison Keys takes the baton as the highest-ranked American on the WTA Insider Clay Court Power Rankings. Where does the rest of the field stand ahead of next week's Porsche Tennis Grand Prix?
WTA Insider Courtney Nguyen
April 17, 2019

World No.2 Simona Halep and No.7 Kiki Bertens remain in the top spots on the WTA Insider Clay Court Power Rankings, but a pair of successful early campaigns have pushed Madison Keys and Caroline Wozniacki up the list of clay-court heavies.

After capturing her first career clay-court title at the 2019 Volvo Car Open, Keys vaulted up four spots from No.10 to No.6 on the Clay Court Power Rankings. The win may have been Keys' first title on the surface, but the American's success on clay over the years has been consistent, culminating last year with a semifinal run at Roland Garros. 

Wozniacki also enjoyed a big boost in Charleston. After making her first final of the season, the Dane surged from No.18 to No.11 on the Clay Court Power Rankings. 

Click here for the previous run of the Power Rankings. 

The WTA Insider Clay Court Power Index is 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 four seasons:

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."

Note that the Power Index formula has been adjusted in 2019. In previous years, 100% of the points earned from the current season and previous season were taken into account. In order to provide a more accurate reflection of recent form, the revised formula takes 100% of the points from the current season and 75% of the previous season.

Madison Keys won her first title in two years, and fourth overall, in Charleston, defeating Caroline Wozniacki 7-6(5), 6-3 in the final (Volvo Car Open/Chris Smith)

Here are 2019's clay court champions so far:

Charleston: Madison Keys d. Caroline Wozniacki
Bogota: Amanda Anisimova d. Astra Sharma
Lugano: Polona Hercog d. Iga Swiatek

READ: Who's Playing Where - Osaka, Halep, Kvitova lead Top 20 into battle on clay

As a refresher, here's who dominated the clay swing in 2018:

Roland Garros: Simona Halep d. Sloane Stephens
Madrid: Petra Kvitova d. Kiki Bertens
Rome: Elina Svitolina d. Simona Halep
Stuttgart: Karolina Pliskova d. CoCo Vandeweghe

Prague: Petra Kvitova d. Mihaela Buzarnescu
Rabat: Elise Mertens d. Ajla Tomljanovic
Strasbourg: Anastasia Pavlyuchenkova d. Dominika Cibulkova
Nuremberg: Johanna Larsson d. Alison Riske
Istanbul: Pauline Parmentier d. Polona Hercog

The Top 20 on the WTA Insider Clay Court Power Rankings, as of April 15th:

No.1 Simona Halep (WTA Rank: No.2)
Career Clay Court Win %:
72.2%
2018 Clay Court Record: 16-3 (84.2%)
Notable recent clay court results: 2018 Roland Garros champion, 2018 Rome finalist, 2018 Madrid semifinalist, 2017 Roland Garros finalist, 2017 and 2016 Madrid champion, 2017 Rome finalist, 2016 Roland Garros Round of 16.

No.2 Kiki Bertens (WTA Rank: No.7)
Career Clay Court Win %:
69.0%
2018 Clay Court Record: 15-5 (75.0%)
Notable recent clay court results: 2018 Madrid finalist, 2018 Charleston champion, 2017 Gstaad champion, 2017 and 2016 Nuremberg champion, 2016 Gstaad finalist.

READ: Bertens chasing pressure-free clay season - 'I feel more freedom on clay'

No.3 Elina Svitolina (WTA Rank: No.6)
Career Clay Court Win %:
64.6%
2018 Clay Court Record: 9-3 (75.0%)
Notable recent clay court results: 2018 and 2017 Rome champion, 2017 Roland Garros quarterfinalist, 2017 Istanbul champion, 2016 Roland Garros Round of 16.

READ: Beyond Svitolina - Behind the scenes of Ukraine's surge in tennis talent

No.4 Garbiñe Muguruza (WTA Rank: No.19)
Career Clay Court Win %:
64.9%
2018 Clay Court Record: 7-4 (63.6%)
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.5 Jelena Ostapenko (WTA Rank: No.29)
Career Clay Court Win %:
63.9%
2018 Clay Court Record: 3-4 (42.9%)
Notable recent clay court results: 2018 Rome quarterfinalist, 2017 Roland Garros champion, 2017 Charleston finalist, 2017 Prague semifinalist.

No.6 Madison Keys (WTA Rank: No.14)
Career Clay Court Win %:
64.9%
2018 Clay Court Record: 11-4 (73.3%)
Notable recent clay court results: 2019 Charleston Champion, 2018 Roland Garros semifinalist, 2018 Charleston semifinalist, 2016 Roland Garros Round of 16, 2016 Rome finalist. 

READ: Madison Keys comes to terms on clay - 'I've held a little bit of a grudge'

No.7 Sloane Stephens (WTA Rank: No.8)
Career Clay Court Win %:
59.6%
2018 Clay Court Record: 12-5 (70.6%)
Notable recent clay court results: 2018 Roland Garros finalist, 2016 Charleston Champion.

READ: 'I was tired of losing! It sucks!' - Stephens finds her fight

No.8. Karolina Pliskova (WTA Rank: No.4)
Career Clay Court Win %:
57.7%
2018 Clay Court Record: 12-4 (75.0%)
Notable recent clay court results: 2018 Stuttgart champion, 2018 Madrid semifinalist, 2017 Roland Garros semifinalist, 2017 Rome quarterfinalist.

No.9 Caroline Garcia (WTA Rank: No.21)
Career Clay Court Win %:
58.8%
2018 Clay Court Record: 13-5 (72.2%)
Notable recent clay court results: 2018 Roland Garros Round of 16, 2018 Rome quarterfinalist, 2018 Madrid semifinalist, 2018 Stuttgart semifinalist, 2017 Roland Garros quarterfinalist, 2016 Strasbourg champion.

No.10 Petra Kvitova (WTA Rank: No.3)
Career Clay Court Win %:
66.4%
2018 Clay Court Record: 15-3 (83.3%)
Notable recent clay court results: 2018 Madrid champion, 2018 Prague champion, 2016 Stuttgart semifinalist.

Here's who rounds out the Top 20:

No.11 Caroline Wozniacki: 1165.50
No.12 Anastasija Sevastova: 1065.25
No.13 Daria Kasatkina: 1053.75
No.14 Samantha Stosur: 1027.50
No.15 Anett Kontaveit: 989.75
No.16 Maria Sharapova: 902.00
No.17 Elise Mertens: 901.00
No.18 Laura Siegemund: 872.75
No.19 Kristina Mladenovic: 863.25
No.20 Irina-Camelia Begu: 854.50