After going undrafted in the 2009 NBA draft, Zeller joined the Chicago Bulls for the 2009 NBA Summer League where he averaged 3.0 points and 2.3 rebounds in four games. On July 31, 2009, he signed a one-year deal with the Shiga Lakestars of the Japanese bj league. In 50 games for Shiga in 2009–10, he averaged 8.2 points and 7.2 rebounds per game.