Zelentsova was born in Novorossiysk on 5 August 1948. Early in her career, Zelentsova competed mostly in the 100 metres hurdles, an event in which she did not reach the international top level; when the women's 400 metres hurdles became a mainstream event in the mid-1970s, she switched to the new event and adapted to it rapidly. In 1976 the women's 400 metres hurdles were contested at the Soviet national championships for the first time; Zelentsova won. She was then sidelined by kidney problems, which required hospitalization and threatened her career; she recovered and returned in top shape. Two weeks before the 1978 European Championships Zelentsova broke the world record in Podolsk, running 55.31. At the European Championships in Prague she broke the record again, winning in 54.89; the silver medalist, Silvia Hollmann of West Germany, was also under the previous world record.