[2] Leușteanu made her debut at the 1954 World Championships in Rome, Italy, where she placed 4th with her team, 5th in the individual combined standings, and was a vault finalist.

The first ever European Artistic Gymnastics Championships for women, held in 1957 in Bucharest in her native country of Romania, saw Leușteanu win the silver in the individual all-around competition behind Soviet Larisa Latynina.

In Moscow at the 1958 World Championships, competing as Elena Teodorescu, she helped her team to the bronze medal and placed 17th in the all around and was, again, a vault finalist.

At the 1960 Rome Olympics, she buttressed her stronger teammate Sonia Iovan, helping their team to the bronze and she was 11th in the individual all around.

She took part in the celebration, ascending to the podium along with other notable Romanian gymnasts of the past such as Nadia Comăneci, Daniela Silivaş, and Lavinia Miloșovici.