| Singles | |
|---|---|
| 2018 Toray Pan Pacific Open | |
| Champion |  Karolína Plíšková |
| Runner-up |  Naomi Osaka |
| Score | 6–4, 6–4 |
Caroline Wozniacki was the two-time defending champion, but lost in the second round to Camila Giorgi.
Karolína Plíšková won the title, defeating Naomi Osaka in the final, 6–4, 6–4. Plíšková won the title after saving two match points Alison Riske had against her in the quarterfinals.
The top four seeds received a bye into the second round.
Caroline Wozniacki (second round)
Caroline Garcia (quarterfinals) Naomi Osaka (final) Karolína Plíšková (champion)
Sloane Stephens (first round)
Garbiñe Muguruza (second round)
Ashleigh Barty (second round) Barbora Strýcová (quarterfinals)| Semifinals | Final | ||||||||||||
 Camila Giorgi | 2 | 3 | |||||||||||
| 3 | Naomi Osaka | 6 | 6 | ||||||||||
| 3 | Naomi Osaka | 4 | 4 | ||||||||||
| 4 | Karolína Plíšková | 6 | 6 | ||||||||||
| 4 | Karolína Plíšková | 6 | 4 | 6 | |||||||||
 Donna Vekić | 2 | 6 | 3 | ||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1/WC | C Wozniacki | 2 | 6 | 4 | |||||||||||||||||||||||
| Q | M Doi | 2 | 1 | C Giorgi | 6 | 2 | 6 | ||||||||||||||||||||
| C Giorgi | 6 | 6 | C Giorgi | 5 | |||||||||||||||||||||||
| WC |  V Azarenka | 6 | 7 | WC | V Azarenka | 3r | |||||||||||||||||||||
| WC | K Nara | 4 | 5 | WC | V Azarenka | 6 | 6 | ||||||||||||||||||||
| C Vandeweghe | 6 | 3 | 5 | 7 | A Barty | 4 | 2 | ||||||||||||||||||||
| 7 | A Barty | 4 | 6 | 7 | C Giorgi | 2 | 3 | ||||||||||||||||||||
| 3 | N Osaka | 6 | 6 | ||||||||||||||||||||||||
| 3 | N Osaka | 6 | 6 | ||||||||||||||||||||||||
| Q | N Hibino | 1 | 7 | 3 |  D Cibulková | 2 | 1 | ||||||||||||||||||||
| D Cibulková | 6 | 5 | 6 | 3 | N Osaka | 6 | 6 | ||||||||||||||||||||
| K Mladenovic | 3 | 65 | 8 | B Strýcová | 3 | 4 | |||||||||||||||||||||
 A Kontaveit | 6 | 77 | A Kontaveit | 65 | 6 | 5 | |||||||||||||||||||||
| Q |  Z Diyas | 4 | 4 | 8 | B Strýcová | 77 | 3 | 7 | |||||||||||||||||||
| 8 | B Strýcová | 6 | 6 | ||||||||||||||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 6 | G Muguruza | 6 | 6 | ||||||||||||||||||||||||
 B Bencic | 2 | 4 | 6 | G Muguruza | 1 | 2 | |||||||||||||||||||||
| Q |  E Bouchard | 4 | 4 | Q | A Riske | 6 | 6 | ||||||||||||||||||||
| Q | A Riske | 6 | 6 | Q | A Riske | 1 | 77 | 64 | |||||||||||||||||||
| WC | Kr Plíšková | 62 | 6 | 68 | 4 | Ka Plíšková | 6 | 65 | 77 | ||||||||||||||||||
| D Gavrilova | 77 | 3 | 710 | D Gavrilova | 6 | 4 | 4 | ||||||||||||||||||||
| 4 | Ka Plíšková | 4 | 6 | 6 | |||||||||||||||||||||||
| 4 | Ka Plíšková | 6 | 4 | 6 | |||||||||||||||||||||||
| 5 | S Stephens | 4 | 4 | D Vekić | 2 | 6 | 3 | ||||||||||||||||||||
| D Vekić | 6 | 6 | D Vekić | 6 | 7 | ||||||||||||||||||||||
| Q | G Dabrowski | 2 | 0 |  J Konta | 3 | 5 | |||||||||||||||||||||
| J Konta | 6 | 6 | D Vekić | 6 | 6 | ||||||||||||||||||||||
 A Pavlyuchenkova | 6 | 6 | 2 | C Garcia | 3 | 4 | |||||||||||||||||||||
| A Sasnovich | 3 | 4 | A Pavlyuchenkova | 4 | 6 | 5 | |||||||||||||||||||||
| 2 | C Garcia | 6 | 2 | 7 | |||||||||||||||||||||||
Zarina Diyas (qualified)
Magda Linette (qualifying competition) Alison Riske (qualified) Eugenie Bouchard (qualified)
Duan Yingying (withdrew) Jana Fett (first round) Nao Hibino (qualified)
Antonia Lottner (qualifying competition) Misaki Doi (qualified) Miyu Kato (withdrew) Ayano Shimizu (qualifying competition) Anna Zaja (first round)| First round | Qualifying competition | ||||||||||||
| 1 | Zarina Diyas | 6 | 6 | ||||||||||
| Miyabi Inoue | 4 | 3 | |||||||||||
| 1 | Zarina Diyas | 6 | 6 | ||||||||||
| Risa Ozaki | 1 | 0 | |||||||||||
| Risa Ozaki | 6 | 77 | |||||||||||
| 12 | Anna Zaja | 2 | 62 | ||||||||||
| First round | Qualifying competition | ||||||||||||
| 2 | Magda Linette | 710 | 6 | ||||||||||
| Momoko Kobori | 68 | 3 | |||||||||||
| 2 | Magda Linette | 2 | 77 | 3 | |||||||||
| 7 | Nao Hibino | 6 | 63 | 6 | |||||||||
| Erika Sema | 0 | 0 | |||||||||||
| 7 | Nao Hibino | 6 | 6 | ||||||||||
| First round | Qualifying competition | ||||||||||||
| 3 | Alison Riske | 6 | 6 | ||||||||||
| Valeria Savinykh | 4 | 4 | |||||||||||
| 3 | Alison Riske | 6 | 6 | ||||||||||
| 11 | Ayano Shimizu | 3 | 2 | ||||||||||
| WC | Mai Hontama | 1 | 4 | ||||||||||
| 11 | Ayano Shimizu | 6 | 6 | ||||||||||
| First round | Qualifying competition | ||||||||||||
| 4 | Eugenie Bouchard | 6 | 6 | ||||||||||
| WC | Moyuka Uchijima | 1 | 1 | ||||||||||
| 4 | Eugenie Bouchard | 6 | 2 | 7 | |||||||||
| WC | Chihiro Muramatsu | 1 | 6 | 5 | |||||||||
| WC | Chihiro Muramatsu | 6 | 6 | ||||||||||
| Alt | Misa Eguchi | 2 | 0 | ||||||||||
| First round | Qualifying competition | ||||||||||||
| Alt | Gabriela Dabrowski | 6 | 6 | ||||||||||
| Miharu Imanishi | 3 | 2 | |||||||||||
| Alt | Gabriela Dabrowski | 6 | 6 | ||||||||||
| 8 | Antonia Lottner | 3 | 2 | ||||||||||
| Mari Osaka | 3 | 6 | 3 | ||||||||||
| 8 | Antonia Lottner | 6 | 4 | 6 | |||||||||
| First round | Qualifying competition | ||||||||||||
| 6 | Jana Fett | 3 | 2 | ||||||||||
| Danielle Lao | 6 | 6 | |||||||||||
| Danielle Lao | 5 | 5 | |||||||||||
| 9 | Misaki Doi | 7 | 7 | ||||||||||
| WC | Haruka Kaji | 0 | 2 | ||||||||||
| 9 | Misaki Doi | 6 | 6 | ||||||||||
Serena Williams defeated Ana Ivanovic in the final, 6–4, 6–1 to win the women's singles tennis title at the 2014 Cincinnati Masters.
Simona Halep was the defending champion, but lost in the second round to Magdaléna Rybáriková.
Simona Halep defeated Jelena Janković in the final, 2–6, 7–5, 6–4 to win the women's singles tennis title at the 2015 Indian Wells Masters.
Karolína Plíšková defeated Angelique Kerber in the final, 6–3, 6–1 to win the women's singles tennis title at the 2016 Cincinnati Masters. It was her sixth WTA Tour singles title.The two would play each other three weeks later, in the final of the US Open; Kerber would avenge her loss by beating Plíšková in three sets.
Agnieszka Radwańska was the defending champion, but lost in the semifinals to Caroline Wozniacki.
Elina Svitolina defeated Caroline Wozniacki in the final, 6–4, 6–0 to win the women's singles tennis title at the 2017 Canadian Open. It was her third consecutive Premier 5 title, making her the first woman to win the first three Premier 5 tournaments in a season, as well as the first to win three consecutive Premier 5 tournaments since Wozniacki won Montreal and Tokyo in 2010 and Dubai in 2011. This was also Wozniacki's sixth consecutive loss in a final in 2017, making her the first to lose that many finals in a row in one season, as well as the first woman to lose six finals in a single season since Maria Sharapova in 2012.
Defending champion Elina Svitolina defeated Simona Halep in a rematch of the previous year's final, 6–0, 6–4 to win the women's singles tennis title at the 2018 Italian Open.
The 2018 Toray Pan Pacific Open is a women's tennis tournament played on indoor hard courts. It was the 35th edition of the Pan Pacific Open, and part of the Premier Series of the 2018 WTA Tour. It took place at the Arena Tachikawa Tachihi in Tachikawa, Tokyo, Japan, on 17–23 September 2018.
Caroline Wozniacki defeated Anastasija Sevastova in the final, 6–3, 6–3 to win the women's singles tennis title at the 2018 China Open. It was Wozniacki's 30th and last WTA Tour title, before her first retirement in January 2020.
Elise Mertens defeated Simona Halep in the final, 3–6, 6–4, 6–3 to win the singles tennis title at the 2019 WTA Qatar Open.
Belinda Bencic defeated Petra Kvitová in the final, 6–3, 1–6, 6–2 to win the women's singles tennis title at the 2019 Dubai Tennis Championships. She saved six match points en route to the title, in the third round against Aryna Sabalenka. For the second time in her career, Bencic defeated four consecutive top-ten players en route to a Premier 5 title. This was her first WTA singles title since winning the Premier 5 Rogers Cup title in 2015, and lifted her back inside the top 25 in rankings for the first time in over two and a half years.
Bianca Andreescu defeated Angelique Kerber in the final, 6–4, 3–6, 6–4 to win the women's singles tennis title at the 2019 Indian Wells Open. It was her first WTA Tour title, and Andreescu became the first wildcard champion in the tournament's history, as well as the youngest champion since Serena Williams in 1999. This marked the second consecutive year where a player won the tournament as her first WTA Tour singles title.
Ashleigh Barty defeated Karolína Plíšková in the final, 7–6(7–1), 6–3 to win the women's singles tennis title at the 2019 Miami Open. It was Barty's first WTA Premier Mandatory title. She entered the top 10 in the WTA rankings for the first time with the win.
Caroline Wozniacki was the defending champion, but lost in the third round to Aryna Sabalenka in a rematch of the previous year's final.
Bianca Andreescu won the women's singles tennis title at the 2019 Canadian Open after Serena Williams retired in the final due to back spasms, with the scoreline at 3–1. Andreescu became the first Canadian to win the event since Faye Urban in 1969.
Madison Keys defeated Svetlana Kuznetsova in the final, 7–5, 7–6(7–5) to win the women's singles tennis title at the 2019 Cincinnati Masters.
Defending champion Aryna Sabalenka defeated Alison Riske in the final, 6–3, 3–6, 6–1 to win the singles tennis title at the 2019 Wuhan Open.
Naomi Osaka defeated Ashleigh Barty in the final, 3–6, 6–3, 6–2 to win the women's singles tennis title at the 2019 China Open. It was Osaka's second Premier Mandatory-level title.
Victoria Azarenka won the women's singles tennis title at the 2020 Cincinnati Masters via walkover, after Naomi Osaka withdrew from the final with a hamstring injury. It was Azarenka's first singles title since the 2016 Miami Open, and her first since giving birth to her son Leo in December 2016.
Simona Halep won the women's singles tennis title at the 2020 Italian Open after the defending champion Karolína Plíšková retired from the final, with the scoreline at 6–0, 2–1. It was her first Italian Open title.