Cologne picked up their first win of the season at Stuttgart whose fans made their dissatisfaction clear to coach Armin Veh.
Bayer Leverkusen claimed a shock 2-0 Bundesliga win at Borussia Dortmund on Saturday, while Hannover beat Schalke.
A crowd of 50,000 watched Cologne play out a goalless draw with Hamburg on their return to the top flight.
Stuttgart followed Mainz out of the DFB-Pokal in the first round, succumbing 2-0 to Bochum, while Marco Reus returned in a victory for Borussia Dortmund.
Bundesliga champions Bayern Munich will launch the defence of their title against Wolfsburg in the 2014/15 season.
Cologne midfielder Sascha Riether is at the centre of a tug-of-war between a Premier League club and a Primera Liga team.
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