Kayla Day

Kayla Day (born September 28, 1999) Her mother is from the Czech Republic.

Juniors She was No. 1 in the girls' 12s, 14s, 16s, and 18s national US rankings. 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.

Professional 2016-2018: Turned pro, first title, major & Premier debuts

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 Lučić-Baroni to reach the third round of the tournament.

2023: French Open third round, top 100 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 Karolína 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.

2024-2026: First WTA 1000-win 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 Świątek, in the second round.

In June 2026, Day qualified to make her main-draw debut at Wimbledon, meaning she had achieved the feat at all four major tournaments. She lost to 26th seed Madison Keys in the first round.

Singles performance timeline Only main-draw results in WTA Tour, Grand Slam tournaments, Billie Jean King Cup, United Cup, Hopman Cup and Olympic Games are included in win–loss records.

Current through the 2024 Guadalajara Open.

ITF Circuit finals Singles: 19 (10 titles, 9 runner-ups) LegendW100 tournaments (2–0)W80 tournaments (0–1)W60/75 tournaments (2–2)W50 tournaments (1–0)W25/35 tournaments (5–5)W15 tournaments (0–1)

Doubles: 6 (4 titles, 2 runner-ups) LegendW100 tournaments W75 tournaments W25/35 tournaments

Junior Grand Slam tournament finals Girls' singles: 1 (title)

Girls' doubles: 1 (runner-up)