Despite clocking her season's best timing, double lap runner Tintu Luka finished sixth in the 800 metre heats at the Rio Olympics here on Wednesday.Tintu started off well but her strategy backfired to finish with a timing of 2:00.58 minutes in Heat 3. Tintu finished overall 29th in the qualification round. The qualification round was topped by Canada's Melissa Bishop followed by Marina Arzamasova of Belarus and Habitam Alemu of Ethiopia respectively at second and third spots.