Hannover inflicted a third straight defeat on new Hertha Berlin coach Michael Skibbe as Mohammed Abdellaoue's goal earned them victory at the Olympiastadion.
Hertha dominated for long stages but could not find a way through as their miserable start to 2012 continued in front of their own fans.
And Abdellaoue punished them with the winner goal in the 68th minute to lift Mirko Slomka's side closer to the top six with their second consecutive 1-0 win.
To make matters worse for the home side, they had Sebastian Neumann sent off 15 minutes from time.
The hosts showed ambition from the off and went close to opening the scoring in the 12th minute when Peter Niemeyer's header was saved in spectacular fashion by Ron Robert Zieler.
Patrick Ebert went close twice for the home side as they continued to pile the pressure on Hannover, who struggled to get out of their own half.
Christopher Avevor came to Hannover's rescue when Zieler was beaten, while the offside flag denied Pierre Lasogga when he found the back of the net just before the interval.
Mame Diouf, signed from Manchester United last month, was given his Hannover debut at the start of the second half as Slomka looked to bring his side to life.
And it proved an inspired change as the Senegal forward set up Abdellaoue to score from just outside the area in the 68th minute.
Hertha kept on pressing, but Neumann's second yellow card in the 75th minute signalled the end of the home side's challenge.
