Ashleigh Barty began 2021 by defeating Garbiñe Muguruza in the final of the Yarra Valley Classic, the Australian's first tour event in 11 months.

Injury forced her to retire from matches at Rome and the French Open, but Barty rebounded by winning Wimbledon, defeating Karolína Plíšková in the final.

On October 23, Barty withdrew from the WTA Finals, citing the toll of spending 8 consecutive months away from home.

Aryna Sabalenka carried her dominant form from the end of 2020 into the start of 2021, winning the first tournament of the year in Abu Dhabi.

A string of three-set losses followed: to Serena Williams in the Australian Open fourth round, to Muguruza in Doha and Dubai, and to Barty in Miami and the final of Stuttgart.

After a first round loss to Paula Badosa in Madrid, Krejcikova held match points against Iga Świątek in Rome.

She did not lose a match for the next eight weeks, winning her first WTA title in Strasbourg and her first singles Grand Slam at the French Open.

At the French Open, Krejčíková saved match points against Maria Sakkari in the semifinals and defeated Anastasia Pavlyuchenkova in three sets in the final.

Barty snapped her winning streak in the fourth round of Wimbledon, but the Czech captured her third title of the year in Prague.

After a third round loss at the Olympics, Krejčíková notched two victories over Muguruza en route to quarterfinals at Cincinnati and the US Open.

Krejčíková is expected to represent the Czech Republic at the Billie Jean King Cup in Prague before making her singles debut at the WTA Finals.

Sakkari had a very strong start to the season reaching consecutive semifinals in Abu Dhabi and Melbourne's Grampians Trophy.

An average clay season culminated into a run to her first ever grand slam semifinal at the French Open where she lost 7–9 in the third set to the eventual champion Krejčíková, despite having a match point.

At the US Open, Sakkari defeated Petra Kvitová, Bianca Andreescu and Karolína Plíšková to reach her second career grand slam semifinal where she lost to the eventual champion, Emma Raducanu.

During the European indoor hardcourt fall season, she reached the final in Ostrava, losing to Anett Kontaveit and semifinal in Moscow where she retired against Ekaterina Alexandrova.

During the fall season, she made the semifinal in Ostrava, losing to Sakkari again and also lost in fourth round at Indian Wells to Jeļena Ostapenko in a battle between two former Roland Garros champions.

She reached the final in just her second event of the season, at Melbourne's Yarra Valley Classic, losing to Barty in the title match.

She won her ninth WTA title in Chicago, defeating Jabeur in the final before losing her opening match in Indian Wells.

After suffering some hiccups in St. Petersburg and Miami, Badosa went on a tear during the clay season, defeating Belinda Bencic and World No.

That pain made Badosa arrive at the US Open not 100% fit, suffering a shocking second round defeat to Varvara Gracheva.

Following a second round loss in Ostrava, Badosa won the second and the biggest title of her career in Indian Wells, with wins over Dayana Yastremska, Coco Gauff, Krejćíková, Angelique Kerber, Ons Jabeur and Victoria Azarenka along the way.

She began working with Dmitry Tursunov in August, and immediately won her first title since 2017 at Cleveland, defeating Irina-Camelia Begu in the final, before losing once again to Świątek, this time at the US Open.