Nuri Sahin and Julian Schuster had successful coaching debuts at Borussia Dortmund and Freiburg, respectively, as Bundesliga clubs avoided upset defeats in the first round of the German Cup on Saturday. Sahin’s Dortmund coasted to a 4-1 success at fourth-division Phoenix Lübeck while Freiburg won 4-0 at third-tier Osnabrück. All other nine top flight sides in action Friday and Saturday also advanced, with the remaining seven playing Sunday, Monday and later in the month. Dortmund go through Former Dortmund and Turkey midfielder Sahin took over from Edin Terzic in summer, and Dortmund made sure…