Japan midfielder Shinji Kagawa netted his first goal of the season when he opened the scoring with a 63-minute strike, but Bundesliga champions Borussia Dortmund lost 2-1 away to Hannover on Sunday.
Karim Haggui struck the equalizer with four minutes left and Didier Konan gave Hannover the lead in the dying seconds.
It was Kagawa's first goal in a league match since December last year.
"The goal went in as I expected when the goalkeeper came out to defend. I would've been happier if we'd won," Kagawa said.
Dortmund has lost three of its opening six games after breezing to the title last season.