With the clay court season headed to a dramatic conclusion at the French Open, who made the biggest gains on the eve of the second Grand Slam of 2017? Check out the updated Clay Court Power Rankings courtesy of WTA Insider.
WTA Insider Courtney Nguyen

Simona Halep's strong clay season puts her atop the WTA Insider Clay Court Power Rankings heading into Roland Garros, which is set to begin on Sunday, May 28th.

The WTA Insider Clay Court Power Rankings is based on an empirical formula that isolates a player's success rate on clay. To measure a player's recent aptitude on the surface, the Insider team applied the following formula:

100% of points earned on clay in 2017
100%
of points earned on clay in 2016
75%
of points earned on clay in 2015
50%
of points earned on clay in 2014

The resulting sum accounts for a player's "Clay Index." For the previous rankings run, click here.

As of the week of May 22nd, here are the current Top 10:

(Note: The Insider Clay Court Power Rankings have been applied to players who are scheduled to play Roland Garros. As such, Serena Williams (Clay Index: 5318.75) and Maria Sharapova (Clay Index: 3629.25), who would have featured on this list if they were scheduled to play, have been set aside.)

It was an honor to have a special guest on court with us today. Thank you Andre? @agassi

A post shared by Simona Halep (@simonahalep) on

No.1 Simona Halep (WTA Rank: No.4)
Clay Index: 5075.75
Career winning percentage on clay: .692
Notable Recent Results: 2017 & 2016 Mutua Madrid Open champion, 2017 Internazionali BNL d'Italia finalist, 2017 Porsche Tennis Grand Prix semifinals, 2014 French Open finalist.

No.2 Garbiñe Muguruza (WTA Rank: No.5)
Clay Index: 3789.25
Career winning percentage on clay: .636
Notable Recent Results: 2016 French Open champion, 2017 & 2016 Rome semifinals, 2014 and 2015 French Open quarterfinals.

Bon jour Paris! @rolandgarros @wta

A post shared by Garbiñe Muguruza (@garbimuguruza) on

No.3 Samantha Stosur (WTA Rank: No.24)
Clay Index: 2864.25
Career winning percentage on clay: .658
Notable Recent Results: 2016 French Open semifinals, 2016 Madrid semifinals.

No.4 Sara Errani (WTA Rank: No.91)
Clay Index: 2650.75
Career winning percentage on clay: .671
Notable Recent Results: 2017 Grand Prix De SAR La Princesse Lalla Meryem semifinals, 2016 Volvo Car Open semifinals, 2014 Rome finalist 2014-2015 French Open quarterfinals.

So happy and excited to back to @rolandgarros ??

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No.5 Elina Svitolina (WTA Rank: No.6)
Clay Index: 2581.25
Career winning percentage on clay: .583
Notable Recent Results: 2017 Rome champion, 2017 Istanbul Cup champion, 2016 French Open Round of 16, 2015 French Open quarterfinals, 2015 Marrakech champion.

No.6 Lucie Safarova (WTA Rank: No.38)
Clay Index: 2510.25
Career winning percentage on clay: .604
Notable Recent Results: 2016 J&T Banka Prague Open champion, 2015 French Open finalist, 2015 Madrid quarterfinal.

No.7 Carla Suárez Navarro (WTA Rank: No.22)
Clay Index: 2391.75
Career winning percentage on clay: .680
Notable Recent Results: 2017 Stuttgart quarterfinals, 2017 Madrid Round of 16, 2015 Rome finalist, 2014 French Open quarterfinals

No.8 Timea Bacsinszky (WTA Rank: No.31)
Clay Index: 2379.75
Career winning percentage on clay: .592
Notable Recent Results: 2016 French Open quarterfinals, 2016 Rabat champion, 2016 Rome quarterfinals, 2015 French Open semifinals.

No.9 Kiki Bertens (WTA Rank: No.19)
Clay Index: 2335.25
Career winning percentage on clay: .632
Notable Recent Results: 2017 Rome semifinals, 2017 Madrid quarterfinals, 2016 French Open semifinals, 2016 Nürnberger Versicherungscup champion, 2016 Rabat semifinals.

No.10 Svetlana Kuznetsova (WTA Rank: No.9)
Clay Index: 2239.25
Career winning percentage on clay: .703
Notable Recent Results: Madrid semifinals, 2016 Rome quarterfinals, 2016 French Open Round of 16, 2015 Madrid finalist, 2014 French Open quarterfinals.

2017 French Open, Roland Garros, Clay Court Power Rankings