Ζακλίν Κριστιάν

2015–2020: WTA Tour debut

Cristian made her WTA Tour main-draw debut at the 2015 Bucharest Open in the doubles event, partnering Elena-Gabriela Ruse. In March 2017, she received a qualifying wildcard for the Miami Open.

Cristian reached her maiden WTA tournament final at the 2019 Bucharest Open in the doubles event, partnering Elena-Gabriela Ruse.

2021: Breakthrough & top 100

She reached the quarterfinals of a WTA event for the first time as a qualifier at the WTA 500 St. Petersburg Ladies' Trophy where she lost to fourth seed Svetlana Kuznetsova. In September, she reached her first semifinal at a WTA tournament at the Astana Open. She reached the quarterfinals of the first edition of the Transylvania Open as a wildcard where she lost to top seed Simona Halep. She began a tradition of wearing a Dracula-like cape on court before or after her matches there. She reached the top 100 on 8 November 2021.

At the Linz Open, she reached the final as a lucky loser following Halep's withdrawal due to injury from the semifinal but lost to Alison Riske in three sets. As a result, she moved 29 positions up in the rankings, having been ranked world No. 100 at the beginning of the tournament.

2022: Major & WTA 1000 debuts & first wins, top 60, hiatus

She made her Grand Slam debut in Melbourne, at the Australian Open where she recorded her first major win against Greet Minnen. As a result, she reached a new career-high ranking of No. 58 on 31 January 2022. At the same event, she reached the third round of the doubles draw on her debut, partnering Andrea Petkovic. She made her WTA 1000 debut at the Qatar Ladies Open as a lucky loser and defeated 11th seed Elena Rybakina for her first win at this level.

She returned after six months of hiatus to make her debut at the US Open where she lost to second seed Anett Kontaveit.

2023–2024: Two WTA 1000 third rounds

She entered the 2023 Australian Open, and the tournaments in Hobart, Linz, and Madrid, and lastly at Wimbledon where she recorded her first win at this major on her debut, using protected ranking.

In the end of January 2024, she entered the WTA 500 Linz Open as a lucky loser and defeated Nadia Podoroska. At home in Cluj Napoca, Romania she reached the semifinals for the first time in her career at the tournament. It was her first WTA Tour semifinal since July 2023 in Prague.

At the 2024 Charleston Open, she defeated three Americans Sachia Vickery, eighth seed Madison Keys and tenth seed Emma Navarro to reach the quarterfinals. As a result she moved back to the top 75 in the rankings.

She reached the third round at the WTA 1000 2024 Madrid Open defeating Magdalena Fręch and 22nd seed Barbora Krejčíková and moved up in the top 70 in the rankings. At the next WTA 1000, the 2024 Italian Open, she entered the main draw as a lucky loser replacing 25th Barbora Krejčíková directly into the second round and defeated Elina Avanesyan to reach again the third round.