In April 2008, Giovanni Trapattoni included Hoolahan in his preliminary 40-man squad for the friendly matches against Serbia on 24 May and Colombia on 29 May. On 13 May, it was confirmed that Hoolahan had made the 28-man squad and that he would be joining a training camp in Portugal on 15 May in preparation for the matches. He came on as a 70th-minute substitute in a practice match which the Irish team drew 1–1 with Portuguese Liga de Honra club side Portimonense. He was an unused substitute in Ireland's 1–1 draw with Serbia at Croke Park in Dublin. On 29 May, he came on as a second-half substitute in the 1–0 win over Colombia held in England at Craven Cottage.