After spending his first season with the club's reserve side, Matmour was eventually promoted to the senior side in the second–half of the 2005–06 season. He made his SC Freiburg first team debut on 28 January 2006, coming on as a substitute for Ibrahim Tanko in the 67th minutes, in a 1–0 win over Dynamo Dresden. In a match against 1860 Munich on 27 February 2006, Matmour set up a goal for Aleksandre Iashvili, who went on to score twice, in a 2–1 win. It wasn't until on 3 May 2006 when he scored his first goals, in a 2–1 win over Hansa Rostock. His assists in the last two matches against Alemannia Aachen and Greuther Fürth saw the club win both matches, but failed to bounce back to Bundesliga after finishing fourth place in the league. At the end of the 2005–06 season, Matmour made a total of 16 appearances and scoring 2 times in all competitions.