He made his Premier League debut on 1 February 2006, replacing Sol Campbell at half time as Arsenal lost 3–2 at home to West Ham United. Due to Campbell's defensive errors in that match, Larsson started the next two league matches in defence in his absence, a 2–0 win away to Birmingham City three days later, and a 1–1 draw at home to Bolton Wanderers on 11 February, in which he was substituted for Dennis Bergkamp as Arsenal sought their equaliser.