Ratnasekera competed only in the women's 50 m freestyle at the 2000 Summer Olympics in Sydney. She received a ticket from FINA, under a Universality program, in an entry time of 29.90. Swimming in heat two, she held off a sprint battle against six other swimmers to overhaul a 30-second barrier and hit the wall first in a sterling time and a Sri Lankan record of 29.88. Ratnasekera's effortless triumph was not enough to put her through to the semifinals, as she placed sixty-fourth overall in the prelims.