Marco Reus scored a dramatic stoppage-time winner as Borussia Dortmund won 3-2 at nine-man Hertha Berlin to move three points clear at the top of the Bundesliga.
Salomon Kalou looked like he would haunt Dortmund again as his double saw the hosts twice move in front, the former Chelsea forward having scored a brace in October's reverse fixture.
Dortmund equalised on each occasion - Thomas Delaney and Dan-Axel Zagadou striking in either half – but had to wait until the final moments to secure victory when Reus side-footed into the bottom corner from Jadon Sancho's cross.
They open up a small gap over Bayern Munich, who do not play until Sunday against Mainz at the Allianz Arena, and will hope this battling victory gives them some much-needed momentum.
In a slump, that has also seen them exit the Champions League, Lucien Favre's men had only won two of their previous six league games, but they now hold the title-race advantage once again.