The 2004 season represented a breakthrough for Zersenay and he established himself as a serious contender in distance running. He signed a contract with Adidas Spain and brought the team victory at the European Clubs' Cross Country Cup in February. The following month he bettered his previous showings at the World Cross Country Championships with a sixth-place finish. With the help of teammates Yonas Kifle and Tesfayohannes Mesfen, among others, he took Eritrea to third position in the team competition – the first time the country had reached the podium at a world cross country event. Two months later he finished second in the 10 km Great Manchester Run; his time of 27:59 was five seconds behind winner Craig Mottram. He took to the track in June at a meeting in Gavà, Spain, and recorded another national record, this time in the 10,000 m with a time of 27:32.61.