She won one of the bronze medals in the 58 kg event at the 2017 European Wrestling Championships held in Novi Sad, Serbia.

[1][2] In 2010, Mertens competed in the girls' freestyle 46 kg event at the Summer Youth Olympics without winning a medal.

In 2013, Mertens competed in the women's 55 kg event at the European Wrestling Championships held in Tbilisi, Georgia where she was eliminated in her second match by Emese Barka of Hungary.

In 2020, Mertens competed in the women's 57 kg event at the Individual Wrestling World Cup held in Belgrade, Serbia where she was eliminated in the repechage by Alyona Kolesnik of Azerbaijan.

[3] In March 2021, she competed at the European Qualification Tournament in Budapest, Hungary hoping to qualify for the 2020 Summer Olympics in Tokyo, Japan.