She challenged five other swimmers on the first heat, including 16-year-old Milica Ostojić of Serbia.
He challenged six other swimmers in heat one, including 34-year-old Mumtaz Ahmed of Pakistan.
She challenged seven other swimmers in heat three, including top medal favorite Anne Poleska of Germany.
He challenged seven other swimmers on the same heat as Sydney, including his former rival Razakarivony.
She challenged seven other swimmers in heat four, including her college teammate Eileen Coparropa of Panama.
He challenged seven other swimmers in heat three, including 16-year-old Chris Hackel of Mauritius.
She challenged seven other swimmers in heat four, including 31-year-old Melanie Slowing of Guatemala.
He challenged seven other swimmers on the seventh heat, including top medal favorite Michael Phelps.
He challenged seven other swimmers in heat five, including Israel's top favorite Tal Stricker.
In the 400 m freestyle, Lehtonen challenged six other swimmers on the second heat, including three from Latin America.