Astana: Sonia Lather assured India at least a silver medal as she stormed into the final in the feather weight (57 kg) class at the Women's World Boxing Championships here on Thursday. The only Indian in the semi-finals in the tournament, Sonia thumped Kazakhastan's Aizhan Khojabekova 3-0 to register a memorable triumph. Sonia completely dominated the bout. Attacking from the very beginning, she timed her jabs and punches to perfection, as she did her defence. Aizhan tried her best in the final round to make a comeback but Sonia's defence kept her on top. Sonia's weight category is not part of Olympic programme. Only three weight categories of 51 kg, 60 kg and 75 kg are part of the women's boxing competitions at the Olympics. However, Sonia's was the only successful story as far as India's participation is concerned. Earlier in the tournament, Indian boxing was dealt heavy blows as veterans M.C. Mary Kom and L. Sarita Devi, and Pooja Rani -- all belonging to Olympics categories -- failed to qualify for the Rio Games after losing in the second rounds.