Rio de Janeiro: Brazilian swimmer Larissa Oliveira set her second South American record in three days when she won the 100 metres freestyle at an Olympic test event here. The 23-year-old on Tuesday swam 54.03 seconds at the Olympic Aquatic Center -- eclipsing by 0.23 seconds off the previous mark held by her compatriot Etiene Medeiros, reports Xinhua. Oliveira has now secured a berth in both 100m and 200m freestyle events at the Rio Olympics in August. On Saturday she set a South American record in the 200m freestyle with a time of 1 minute, 57.37 seconds. There was drama in the men's 200m medley final, which ended in a dead heat between Thiago Perreira and Henrique Rodrigues. Both swimmers are guaranteed of their Olympic berths. In the 200m backstroke, Leonardo de Deus secured a Games spot by winning the final in 1 minute, 56.57 seconds.