Saxony Cup
In 2010, Sebastian returned to his hometown, joining RB Leipzig on a four-year contract and being immediately appointed captain. On 6 August 2010, Sebastian made his debut for RB Leipzig in a 1–1 draw with Türkiyemspor Berlin. He appeared in 27 league matches in his first season scoring one goal as the club finished its first season in the Regionalliga in fourth place, thus missing out on promotion. However, under coach Tomas Oral, the club succeeded in winning the 2010–11 Saxony Cup after defeating Chemnitzer FC 1–0 in the final on 1 June 2011 in front of 13,958 spectators at the Red Bull Arena. By winning the 2010–11 Saxony cup, the club won its first title in club history. It also qualified to participate in the 2011–12 DFB-Pokal. For the following seasons he was a key contributor in helping the club gain promotion from Regionalliga Nordost all the way up to the 2. Bundesliga. He extended his contract at RB Leipzig on 4 April 2014 for another year until 2015, with a possibility for another year of extension.