Borussia Dortmund defender Mats Hummels has admitted that he was not happy with the manner of his side's victory over Werder Bremen on Friday.
The defending German champions began the 2012-13 Bundesliga campaign with a narrow 2-1 win at home, thanks to goals from Marco Reus and Mario Gotze.
"The result was good, but I am not happy with the manner," said Hummels. "The most important thing is to earn three points.
"Last year we had a great start and after that we had five very poor games. Maybe it is better to know that we still have work to do."
Dortmund's next game in the Bundesliga is against Nurnberg on Saturday, September 1.
