 After playing with Werder Bremen II Rost made his Bundesliga debut during the 1995–96 season and became first-choice keeper during the 1998–99 season.At the end of this season he helped Bremen win the 1998–99 DFB-Pokal.The final against Bayern Munich went to penalties and Rost scored a penalty himself before saving from Lothar Matthäus to win Bremen the cup.