[2] In December 2021, she completed a remarkable late-season surge as singles and doubles victories at the prestigious Orange Bowl championships saw her climb nine places to finish as the year-end junior world No.

[3] At the beginning of 2022, she won her first junior Grand Slam title at the Australian Open, defeating Sofia Costoulas in the final, in straight sets.

[4] Marčinko made her WTA Tour debut at the 2022 Morocco Open in Rabat defeating Rebecca Peterson,[5] before losing to Astra Sharma in the second round.

[6] She won her sixth consecutive ITF Women's Circuit title at the 2023 Caldas da Rainha Ladies Open, defeating Léolia Jeanjean in the final in straight sets, and set the new Croatian record for the youngest women's player to win six professional singles titles before turning 18.

[7] Having been given a wildcard entry, Marčinko was runner-up at the WTA 125 2024 Montreux Nestlé Open, losing to seventh seed Irina-Camelia Begu in the final in three sets.