Unable to break into the first team, however, after their second term with the reserves, the twins were separated; while Henrik was dispatched to Assyriska in Sweden, Niklas remained in the Netherlands, where he signed with FC Zwolle instead. FC Zwolle On 3 May 2006 it was announced that Moisander would transfer to the Eerste Divisie side FC Zwolle, signing a two-year contract with the club from Overijssel. He made his debut on 11 August 2006 in a 2–0 win at home against Fortuna Sittard in the KNVB Cup match, at which point he immediately establishing his position in the starting XI of the team. Midway through his first season, his contract was annulled and extended for an additional year, binding him to the club until the summer of 2009. After his first two seasons, and with one year still remaining on his contract, Zwolle and AZ agreed to terms for a direct transfer of Moisander for a reported €600,000 transfer fee, returning to the top flight of Dutch football. During his stay in Zwolle, he made 75 appearances for the club, scoring five times, where he was an instrumental player for his side. AZ On 11 July 2008, it was announced that AZ had come to terms with Zwolle for the direct transfer of Moisander, signing a three-year contract to bind him to the club until the summer of 2011. He made his Eredivisie debut on 20 September 2008 for AZ in its 1–0 home win against Dutch giants PSV. He scored his first goal for AZ on 3 October 2008 in the 6–0 regular season victory over Sparta Rotterdam. He was able to establish himself as the first choice defender under manager Louis van Gaal, playing a total of 22 full league matches, having briefly been sidelined in the months of January and February due to a knee injury. Moisander quickly came back to help his side win the Eredivisie title, the second for the club in its history and Moisander's personal first. That season, the title race had come down to the final round, and although AZ had lost their last game of the season against Vitesse, it was still able to consequently clinch the league due to eminent losses suffered by title contenders Ajax and Twente. The following season, Moisander made his continental debut, playing in the 2009–10 UEFA Champions League group stage campaign. Playing in