Kayla Day (born September 28, 1999) is an American professional tennis player. She has a career-high singles ranking of world No. 84 by the WTA reached in April 2024. As a junior, she won the 2016 US Open in singles and was a finalist in doubles, partnering with Caroline Dolehide.
Day plays mostly on the ITF Women's Circuit and the WTA 125 Challenger Tour.
Day started playing tennis when she was seven years old. Her mother is from the Czech Republic.
She was No. 1 in the girls' 12s, 14s, 16s, and 18s national US rankings. In 2016, Day climbed to the top of the ITF junior rankings by winning the 2016 Junior US Open, reaching semifinals at the 2016 Wimbledon, and reaching the final at the Orange Bowl the previous year. She also achieved her best doubles result at a major event as a runner-up at the 2016 Junior US Open with partner Caroline Dolehide. She won the 2016 USTA Girls 18s National Championships to earn a wildcard into the main draw of the US Open. Day has been coached from the beginning by Larry Mousouris, who has coached two other Junior US Open winners, Michael Falberg and Tim Trigueiro.
Day made her WTA Tour debut at the 2016 Connecticut Open in New Haven, after reaching the main draw as a lucky loser, having defeated Naomi Broady and Kirsten Flipkens along the way. The following week, she played in her first career Grand Slam at the 2016 US Open, and won her first match against compatriot Madison Brengle.
Shortly after turning 17, Day won her first career title at the 50k tournament in Macon, Georgia. The following week at Scottsdale, she reached the semifinals to enter the top 200 for the first time. With her combined performance at these two events, she won the Australian Open Wild Card Challenge to earn a spot in the main draw at the first major event of 2017. She officially turned professional in 2017, at the Australian Open. Day picked up her first WTA Tour wins of the 2017 season, and first wins of her career at a Premier Mandatory event in Indian Wells, including a victory over 2017 Australian Open semifinalist Mirjana LuÃÂiÃÂ-Baroni to reach the third round of the tournament.
After almost five years of absence at the WTA 1000 level, she qualified for the main draw at the Guadalajara Open where she lost in the first round to Eugenie Bouchard.
Day won three matches in the French Open qualifying to make her first main draw at Roland Garros, as well as her first Grand Slam tournament appearance since the 2017 US Open. She defeated wildcard Kristina Mladenovic and 20th seed Madison Keys to reach the third round of a major for the first time. Day lost to Anna KarolÃÂna Schmiedlová in the third round.
She claimed the title at the Championnats de Granby, defeating Katherine Sebov in the final and moving to world No. 94 as a result.
Day lost to Viktoriya Tomova in the first round of the 2024 Australian Open.
At the 2024 Indian Wells Open, she entered the main draw as a lucky loser replacing fourth seed and defending champion, Elena Rybakina, directly in the second round where she lost to Nadia Podoroska. She reached a career-high ranking of No. 84 on April 1, 2024.
Day lost to lucky loser Hailey Baptiste in the first round at the 2024 French Open.
In September 2025, she won her seventh professional title on her 26th birthday at the 2025 Central Coast Pro Tennis Open in Templeton, California.
Day qualified for the 2026 Indian Wells Open and defeated Francesca Jones, before losing to second seed Iga à Âwiàtek in the second round.
Only main-draw results in WTA Tour, Grand Slam tournaments, Billie Jean King Cup, United Cup, Hopman Cup and Olympic Games are included in winâÂÂloss records.
Current through the 2023 Korea Open.