Germany joined France in the quarter-finals of the women's World Cup from Group A after the hosts and defending champions spluttered to a 1-0 win over Nigeria on Thursday.
After their impressive 2-1 win over Canada on Sunday, this was a less assured performance from two-time winners Germany, who took nearly an hour to impose themselves against a bruising Nigerian side.
Midfielder Simone Laudehr scored the crucial second-half goal and Germany will now take on France in both teams' final group game in Moenchengladbach next Tuesday to decide who will finish top of the group.
Nigeria will be heading home after their final match against Canada in Dresden the same day, when both teams will be playing for pride after two successive defeats.
Germany failed to impose themselves on a Nigerian team whose coach Eucharia Uche has sparked controversy at this tournament by making several anti-homosexual comments, but her team have failed to impress on the pitch.
They made life hard for Germany, however, and the hosts failed to get a clear shot on goal in the first half and were briefly booed by the sell-out crowd at the half-time whistle with the game scoreless.
Germany finally took the game by the scruff of the neck after the break and it was the introduction of the experienced Inka Grings on 52 minutes for captain Birgit Prinz that made an impact.
Barely two minutes later, the veteran forward latched onto a free-kick and her delicate backheel fell into the path of Laudehr, who fired home in plenty of space.
The Africans certainly made their presence felt as Frankfurt midfielder Melanie Behringer had to come off after only half an hour after taking a knock to the leg.
Prinz, Germany's record goal-scorer and most capped player, who was making her 215th appearance, was also left on the bench with her leg heavily strapped.
With time almost up, Germany coach Silvia Neid threw on playmaker Fatmire Bajramaj, but the winger failed to make an impact even as the spaces opened up in the dying stages.
Having won the 2003 and 2007 editions of the World Cup, Germany will need to raise their game if Neid's side are going to return to Frankfurt on July 17 to contest the final of the three week-long tournament.