Petra Marcinko carried the heaviest junior résumé Croatia had produced in a generation long before she could legally drink. In December 2021 a late-season surge — singles and doubles wins at the Orange Bowl — pushed her to year-end junior world No. 1, and at the start of 2022 she won her first junior Grand Slam title at the Australian Open, defeating Sofia Costoulas in the final in straight sets. Born in Zagreb on December 4, 2005, she came up under coach Goran Prpić and turned pro in 2021 while still active on the junior circuit.
She's a right-handed aggressive baseliner who lives on depth and a heavy two-handed backhand, with clay her most productive surface — her career hard record sits around 64%, but on clay she's at roughly 68%. The flip side is the serve: the second ball can leak, and she has averaged close to four double faults per match in recent best-of-three play.
The breakthrough took time. Her best early Tour result was an R16 at Monastir in 2023, where she lost to eventual runner-up Jasmine Paolini. In 2025 she won a WTA 125 title in Rome on clay and closed the year with an ITF W100 at Dubai — the run that finally pushed her into the top 100. The defining week came at the 2026 Morocco Open in Rabat: seeded sixth, she took her maiden Tour title past Vera Zvonareva, Yelyzaveta Kotliar, second seed Jéssica Bouzas Maneiro and Jil Teichmann before Anhelina Kalinina retired hurt in the final. The trophy carried her to a career-high world No. 51 on May 25, 2026.
The trophy hangover was immediate: she fell to Eva Lys in the French Open first round, her main-draw debut in Paris. Settling among the seeds at a level she only recently reached is the next test.