Sahin told the Bundesliga's official website: "We're heading very much in the right direction. I'm looking forward to everything, to every competition.
"We hit a good run of form at the end of last season, but we need to become even more effective. Conceding fewer goals and in the best case scenario, scoring more as well."
The 24-year-old is currently back at Dortmund on an 18-month loan deal, with the former German champions believed to be weighing up a permanent move for a player who started his professional career with them.