Leylah A Fernandez

On 25 January 2019, as a 16-year old, Fernandez entered the Australian Open girls' singles final, where she lost to the top-seeded Clara Tauson. On 8 June 2019, Fernandez defeated Emma Navarro in the French Open final to become the first Canadian female winner of a junior Grand Slam title since Eugenie Bouchard at the 2012 Wimbledon Championships, a victory that earned her the world No. 1 junior ranking.

On 21 July 2019, Fernandez won her first professional singles tennis title when she rallied to beat fellow Canadian Carson Branstine in the final of the Gatineau Challenger. Fernandez also won her first professional doubles title on the same date when she teamed with Rebecca Marino of Vancouver. The pair defeated the second-seeded team of Marcela Zacarías of Mexico and Hsu Chieh-yu of Taiwan. The following week, she made her second consecutive ITF final in Granby, losing to Lizette Cabrera of Australia.

Fernandez made her Grand Slam debut at the Australian Open. After qualifying, she lost in the first round to Lauren Davis.

She achieved the biggest win of her career the following week in the 2020 Billie Jean King Cup qualifying round against world No. 5, Belinda Bencic.

In late February, at the Mexican Open, she qualified and reached her first WTA Tour final. After winning 12 sets in a row, she was defeated by world No. 69, Heather Watson. A week later, she upset Grand Slam champion Sloane Stephens to reach the quarterfinals of the Monterrey Open, losing to the eventual champion, Elina Svitolina.

In October at the French Open, Fernandez reached the third round, first by upsetting 31st seed Magda Linette in the opening round, and then defeating Polona Hercog, before losing to Petra Kvitová, in straight sets.

Fernandez began 2021 without consecutive wins in her first four tournaments. However, in March at the Monterrey Open, she won her first four matches to reach the final, defeating Viktorija Golubic to win the first WTA Tour title of her career. At 18 years old, she was the youngest player in the main draw, and won without dropping a set during the tournament.

At the US Open, Fernandez became a fan favorite due to her success as an underdog. She defeated the third seed and defending champion, Naomi Osaka, in three sets in the third round, former world-number-one and three-time major champion, Angelique Kerber, in the fourth round, in three sets, and fifth seed Elina Svitolina in the quarterfinals, again in three sets, to reach her maiden major semifinal a day after her 19th birthday. She then defeated Aryna Sabalenka, the second seed, to reach her first major final and also the first player born in 2002 to reach such a final. It was the third time in the Open era that a woman defeated three of the top five seeds at the US Open.^[] In the final, she lost to fellow teenager Emma Raducanu, in straight sets.

Fernandez then made her Indian Wells Open debut as the 23rd seed. She first beat Alizé Cornet in the second round and French Open finalist Anastasia Pavlyuchenkova in the third, before suffering an upset in round four by Shelby Rogers.

At the end of the year, Fernandez was given the Bobbie Rosenfeld Award by the Canadian Press as its choice for Canadian female athlete of 2021.

Fernandez started the season at the Adelaide International where she advanced to the round of 16, in which she was defeated by Iga Świątek, in straight sets. She lost to Maddison Inglis in the opening round of the Australian Open as the 23rd seed.

In March, Fernandez defended her Monterrey Open title, reaching her fourth final and winning her second career title. Beating Anna Karolína Schmiedlová, Zheng Qinwen, Wang Qiang and Beatriz Haddad Maia to reach the final, Fernandez won against Camila Osorio in three sets, saving five championship points in the final set. She also entered the doubles competition with her sister, Bianca Fernandez. They lost in the first round to Elixane Lechemia and Ingrid Neel.

Fernandez subsequently entered the Indian Wells Open. Receiving a bye in the first round, she advanced to round three after a retirement from Amanda Anisimova. In her third-round match, she won the second-set tiebreak and defeated Shelby Rogers in three sets, before losing to defending champion Paula Badosa in the fourth. In the doubles competition, partnering with Alizé Cornet, the pair reached semifinals losing there to eventual champions Xu Yifan and Yang Zhaoxuan.

In May, at the French Open, Fernandez beat Olympic champion Belinda Bencic and 2019 French Open semifinalist Amanda Anisimova in the third and fourth rounds, respectively, before losing to Martina Trevisan in the quarterfinals.

A Grade-III-fractured foot acquired during her quarterfinal match with Trevisan forced her to miss Wimbledon, after a first-round exit the previous year to Jeļena Ostapenko.

At the Canadian Open, Fernandez lost in the second round to eventual finalist Beatriz Haddad Maia. At the Cincinnati Open, she lost in the first round to Ekaterina Alexandrova.

Fernandez entered the US Open seeded 14th. In her opening round, she defeated Océane Dodin, before losing to Liudmila Samsonova. With the loss of most of her points from reaching the final last year, Fernandez is set to fall outside of the top 30. In the doubles draw, pairing with Daria Saville, she reached the second round, and with Jack Sock in the mixed doubles the quarterfinals.

Fernandez started the season by reaching the quarterfinals at the Auckland Open. At the Australian Open, she won her first-round match against Alizé Cornet. In the second round, she lost to world No. 4, Caroline Garcia, in a hard-fought match, having set points in both sets.

At the Miami Open in the doubles competition, partnering with Taylor Townsend, they reached the final where they lost to American No. 1 duo Coco Gauff and Jessica Pegula. As a result, she moved up 40 positions to a new career-high of No. 42 in the doubles rankings, and later in beginning of May to No. 36.

At the French Open in singles, she reached the second round but lost to Clara Tauson. At the same tournament, in doubles, she reached her first major doubles final alongside Taylor Townsend. As a result, she moved into the top 20 in the doubles rankings, on 21 August 2023. At Wimbledon, Fernandez lost in the second round to Garcia in a third-set tiebreak. With Townsend, she again lost to Garcia and her partner Luisa Stefani in the second round of the women's doubles, and partnered with Wesley Koolhof in the mixed doubles, losing in the second round.

Fernandez had mixed results during the US Open swing. She lost to Maria Sakkari in the second round of Washington Open, and scored a win against 11th seed Beatriz Haddad Maia in the second round of the Canadian Open, before losing to Danielle Collins. After failing to qualify for the Cincinnati Open, Fernandez reached the quarterfinals of Tennis in Cleveland. Fernandez was knocked out of the US Open in the first round by Ekaterina Alexandrova, but again with Townsend, reached the quarterfinal of the women's doubles losing to eventual champions, Erin Routliffe and Gabriela Dabrowski.

Fernandez showed better results post US Open swing. She reached her first WTA 1000 singles quarterfinal at the Guadalajara Open, losing there to Sofia Kenin. At the same tournament, she also made the quarterfinals in doubles with Townsend.

At the beginning of the Asian swing, Fernandez failed to qualify for the China Open, but won her first title since February 2022 at the Hong Kong Open, defeating Victoria Azarenka, Mirra Andreeva, Linda Fruhvirtová, Anna Blinkova and Kateřina Siniaková. With her title, she reentered the top 50 at No. 43 for the first time, since she dropped her Roland Garros quarterfinal points in May. At the next Asian tournament, the Jiangxi Open, she lost this time to Siniaková in the semifinals. She climbed back to the top 35 in the singles rankings and set a new career-high in doubles of No. 17, on 23 October 2023.

Fernandez led the Canadian team to victory at the 2023 Billie Jean King Cup, winning her four singles matches and one doubles match, and defeating her first top ten opponent (Markéta Vondroušová) since the 2021 US Open. This was Canada's first ever Cup win, immediately hailed as a major moment in the history of Canadian tennis, and Fernandez was widely singled out for praise for her contributions. She said that the achievement "means the world to me," adding that it "gives me a lot of confidence, but also the group of girls and Canada a lot of confidence." Fernandez won the Heart Award for both the Qualifiers and the Finals, becoming only the second player in history to win the award twice in one season.

At her home tournament, the Canadian Open in Toronto, she reached the doubles semifinals with her sister Bianca where they lost to Gabriela Dabrowski and Erin Routliffe. At the next WTA 1000, the Cincinnati Open, she reached the quarterfinals in singles with victories over fourth seed Elena Rybakina, her first win over a top five ranked opponent since her run to the 2021 US Open final, and Diana Shnaider. She lost in the last four to Jessica Pegula. Partnering with Yulia Putintseva, Fernandez reached the final of the doubles at the same event but the pair lost to Asia Muhammad and Erin Routliffe in a champions tie-break decider.