Lalova's parents, Miroslav Lalov and Liliya Lalova, were athletes. Miroslav was the Bulgarian 200 metres champion in 1966. Lalova began competing in swimming and gymnastics at age 10, and soon switched to track and field. She became the Bulgarian Youth champion in the 100 metres competition in 2000, and placed fourth in the 200 metres at the 2001 IAAF World Youth Championships. At the 2003 European Athletics Junior Championships, she won both the 100 metres and 200 metres events.