In the 2007–08 season, Haroun made his UEFA Champions League debut, where he started the whole game, in a 2–1 loss against FK Sarajevo in the first leg of the UEFA Champions League Second Qualifying Round. However, he was demoted to the substitute bench for the next two matches for the side, due to strong competition in the midfield and attacking positions. Haroun made his return to the starting line–up against Germinal Beerschot on 25 August 2007, and set up the club's second goal of the game, in a 2–1. Since returning to the starting line–up, he regained his first team place for the next six matches before missing out with a thigh injury. It wasn't until on 10 November 2007 when Haroun made his return to the starting line–up, in a 1–0 win against Charleroi. However, he announced his intention to leave Genk, due to being unhappy being placed on the substitute bench. Amid to the transfer speculation, Haroun scored his first goal of the season, in a 5–1 loss against Cercle Brugge on 20 January 2008. Eventually, he stayed and later regained his first team place for the side for the rest of the season. He then scored two goals in two matches between on 21 March 2008 and 30 March 2008 against Royal Excel Mouscron and Club Brugge. Haroun then scored his fifth goal of the season, in a 2–2 draw against Zulte Waregem on 2 May 2008. At the end of the 2007–08 season, he went on to make thirty appearances and scoring four times in all competitions.