Sentayehu made her international championship debut at the 2001 World Youth Championships in Athletics and took the bronze medal in the 1500 metres. She soon changed her focus to longer distances and competed on the 2002 IAAF Golden League circuit, recording a 3000 metres best of 8:48.30 minutes at the Weltklasse Zurich at the age of seventeen. She gained a place at the 2002 IAAF Grand Prix Final and came seventh in the event. A sixth-place finish in the junior race at the 2003 IAAF World Cross Country Championships helped the Ethiopian women to the team title, while fellow Ethiopian Tirunesh Dibaba won the race. She improved her 3000 m track best to 8:46.51 that year but an appearance at the 2003 IAAF World Athletics Final resulted in another seventh-place finish.