Lewis emerged onto the national athletics scene in 1994, winning several events at the Australian Championships: the Under-16 100 m/200 m double and the Under-20 400 m. After these performances she was chosen, aged 15, for the 1994 Commonwealth Games as a 4 x 400 metres relay runner, though she did not eventually compete in the event. Her next international selection was for the 1996 World Junior Championships in Sydney, where she won a bronze medal as part of the Australian 4 x 400 metres relay team.