Australian Open champion and World No.1 Naomi Osaka and Sydney International champion and World No.2 Petra Kvitova surged up the WTA Insider Hard Court Power Index after their January exploits, but it's Brisbane International champion and World No.5 Karolina Pliskova who tops the charts after the Australian swing. 

READ: Pliskova soaks up the Aussie Summer

The WTA Insider Hard Court Power Rankings are based on an empirical formula that isolates a player's success rate on hard 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 hard courts in 2019
75% of points earned on hard courts in 2018
50% of points earned on hard courts in 2017
25% of points earned on hard courts in 2016

The resulting sum accounts for a player's "Hard Court Index." Click here to see how the Power Index looked ahead of the Australian Open.

It should surprise no one that the three women who had the most successful season starts Down Under - Pliskova, Osaka, and Kvitova - made the most meaningful gains up the leaderboard. With her 10-1 start to the season, which included the title in Brisbane and her first Australian Open semifinal, Pliskova overtakes 2018 Australian Open champion Caroline Wozniacki to sit at No.1. 

Newly-minted World No.1 Osaka continues her meteoric rise. The 21-year-old is the reigning champion of 3 of the 6 biggest hardcourt tournaments of the last 12 months: Australian Open, US Open, and Indian Wells. With her second major title, Osaka moved up 3 spots to No.3. 

READ: Osaka Champions Corner - 'I didn't think I'd be in this position so soon again'

World No.2 Petra Kvitova saw her 11-match win-streak snapped by Osaka in the Melbourne final, but the Czech showed no signs of slowing down after her inspired 2018 campaign. She earned the biggest jump in the Top 10, moving up 4 spots to No.5.

After making her second consecutive Sydney final and her first Slam quarterfinal at the Australian Open, Ashleigh Barty enjoyed the biggest bump of any of the women previously featured on the Power Index, moving up 7 spots to No.11. 

St. Petersburg Ladies Trophy champion Kiki Bertens, who also made the semifinals in Sydney, continued to find comfort on the hardcourts to start her season. With her triumph in Russia, the World No.8 makes her Hard Court Power Index debut at No.17.

READ: Kiki Bertens 'hungrier than ever' after perfect pre-season

As a refresher, here's how the Middle East swing played out last year:

Qatar Total Open: Petra Kvitova d. Garbiñe Muguruza, 3-6, 6-3, 6-4.
Dubai Duty Free Tennis Championships: Elina Svitolina d. Daria Kasatkina, 6-4. 6-0. 

Here are the Top 20 on the WTA Insider Hard Court Power Rankings heading into the Middle East Swing in Doha (Premier) and Dubai (Premier 5).

READ: Where the Top 20 are playing in February

No.1 Karolina Pliskova (WTA Rank: No.5)
2019 Hard Court Record: 
2018 Hard Court Record: 32-16
Recent Hard Court Results: 2019 & 2016 Brisbane International champion, 2019 Australian Open semifinalist, 2018 & 2017 WTA Finals semifinalist, 2018 Tianjin Open champion, 2018 Toray Pan Pacific Open champion, 2018 US Open quarterfinalist, 2018 Australian Open quarterfinalist, 2017 US Open quarterfinalist, 2017 Cincinnati semifinalist, 2017 Miami semifinalist, 2017 Indian Wells semifinalist, 2017 Doha champion, 2017 Australian Open quarterfinalist, 2017 Brisbane champion, 2016 US Open finalist, 2016 Cincinnati champion, 2016 Indian Wells semifinalist.

No.2 Caroline Wozniacki  (WTA Rank: No.10)
2019 Hard Court Record:
2018 Hard Court Record: 26-12
Notable Hard Court Results: 2018 China Open champion, 2018 Doha semifinalist, 2018 Australian Open champion, 2018 Auckland finalist, 2017 WTA Finals champion, 2017 Tokyo champion, 2017 Toronto finalist, 2017 Miami finalist, 2017 Dubai finalist, 2017 Doha finalist, 2016 Hong Kong champion, 2016 Tokyo champion, 2016 US Open semifinalist.

No.3 Naomi Osaka (WTA Rank: No.1)
2019 Hard Court Record:
2018 Hard Court Record: 29-13
Recent Hard Court Results: 2019 Australian Open champion, 2019 Brisbane semifinalist, 2018 China Open semifinalist, 2018 Tokyo finalist, 2018 US Open champion, 2018 Indian Wells champion, 2016 Tokyo finalist.

No.4 Elina Svitolina (WTA Rank: No.7)
2019 Hard Court Record:
2018 Hard Court Record: 33-10
Recent Hard Court Results: 2019 Australian Open quarterfinalist, 2018 WTA Finals champion, 2018 Montreal semifinalist, 2018 & 2017 Dubai champion, 2018 Australian Open quarterfinalist, 2018 Brisbane champion, 2017 Toronto champion, 2017 Taipei champion, 2016 Beijing semifinalist, 2016 New Haven finalist, 2016 Kuala Lumpur champion. 

No.5 Petra Kvitova (WTA Rank: No.2)
2019 Hard Court Record:
2018 Hard Court Record: 26-13
Recent Hard Court Results: 2019 Australian Open finalist, 2019 Sydney champion, Cincinnati semifinalist, Doha champion, St. Petersburg champion, 2017 Beijing semifinalist, 2017 US Open quarterfinalist, 2016 Zhuhai champion, 2016 Luxembourg finalist, 2016 Wuhan champion.

No.6 Simona Halep (WTA Rank: No.3)
2019 Hard Court Record:
2018 Hard Court Record: 28-7
Notable Hard Court Results: 2018 Cincinnati finalist, 2018 Montreal champion, 2018 Indian Wells semifinalist, 2018 Doha semifinalist, 2018 Australian Open finalist, 2018 Shenzhen champion, 2017 China Open finalist, 2017 Cincinnati finalist, 2017 Toronto semifinalist, 2016 Wuhan semifinalist, 2016 US Open quarterfinalist, 2016 Cincinnati semifinalist, 2016 Montreal champion.

No.7 Angelique Kerber (WTA Rank: No.6)
2019 Hard Court Record:
2018 Hard Court Record: 28-12
Recent Hard Court Results: 2018 Australian Open semifinalist, 2018 Sydney champion, 2017 Monterrey finalist, 2017 Dubai semifinalist, 2016 WTA Finals finalist, 2016 US Open champion, 2016 Cincinnati finalist, 2016 Montreal semifinalist, 2016 Miami semifinalist, 2016 Australian Open champion, 2016 Brisbane finalist.

No.8 Sloane Stephens (WTA Rank: No.4)
2019 Hard Court Record:
2018 Hard Court Record: 25-13
Recent Hard Court Results: 2018 WTA Finals finalist, 2018 US Open quarterfinalist, 2018 Montreal finalist, 2018 Miami Open champion, 2017 US Open champion, 2016 Acapulco champion, 2016 Auckland champion. 

No.9 Garbiñe Muguruza (WTA Rank: No.15)
2019 Hard Court Record:
2018 Hard Court Record: 24-14
Recent Hard Court Results: 2018 Monterrey champion, 2018 Dubai semifinalist, 2018 Doha finalist, 2017 Cincinnati champion, 2017 Australian Open quarterfinalist, 2016 Cincinnati semifinalist.

No.10 Caroline Garcia (WTA Rank: No.19)
2019 Hard Court Record:
2018 Hard Court Record: 24-15
Recent Hard Court Results: 2018 Tianjin Open champion, 2017 WTA Finals semifinalist, 2017 Beijing champion, 2017 Wuhan champion.

Here's who rounds out the Top 20:

No.11 Ashleigh Barty: 3,333.00 (+7)
No.12 Serena Williams: 3,234.50 (+3)
No.13 Madison Keys: 3215.25 (=)
No.14 Anastasija Sevastova: 3,117.50 (=)
No.15 Venus Williams: 3,112.75 (-3)
No.16 Julia Goerges: 3,071.25 (-5)
No.17 Kiki Bertens: 3,025.50 (debut)
No.18 Aryna Sabalenka: 2,946.75 (-1)
No.19 Johanna Konta: 2,849.75 (-3)
No.20 Daria Kasatkina: 2,652.00 (-1)

*Note: 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.