In his earliest international outing, Fredericks won a bronze medal in the 110 metres hurdles and a silver medal in the 400 m hurdles at the 2006 Gymnasiade. He was fifth in the 400 m event at the 2007 World Youth Championships in Athletics and improved to fourth place at the 2008 World Junior Championships. Later that year he ran at the 2008 Commonwealth Youth Games, coming second in the 110 m hurdles and helping the South African 4×400 metres relay team to fourth place. In his final year of junior competitions, he won both the hurdles events at the 2009 African Junior Athletics Championships as well as a silver medal in the relay.