In 2008, he ran at the São Silvestre da Amadora road race, winning the 10 km competition in 29:27. Merga won the Antrim International Cross Country in early 2009 and went on to finish second behind Gebregziabher Gebremariam at the Ethiopian 10,000 m championships in July. He finished fourth in the 10,000 metres at the 2009 World Championships and won the 5000 metres at the 2009 World Athletics Final. He closed the year on the cross country circuit, winning at the Cross de l'Acier for a third consecutive time.