 Sellar represented Australia in the International Rules Youth Test between Australia and Ireland, and has also represented Australia in volleyball, in the Under-19 Internationals in Taiwan.He was named best player at the national Under 16 Championships in 2005 and also played in the Under 18 national championships in 2006.He spent most of his early AFL career playing for Glenelg in the South Australian National Football League (SANFL), playing only a handful of games for the Crows despite being named as an emergency on numerous occasions.