In what was billed as a "six-pointer" at the bottom of the table, a late winner for Hertha Berlin secured a hugely important three points. Hamburg, meanwhile, are left struggling near the relegation zone.
Hamburg 0-1 Hertha Berlin
Sebastian Langkamp's 84th minute winner for Hertha Berlin left HSV coach Josef Zinnbauer slumped in his seat in the dugout. Without a win in six games, Friday's defeat at the hands of another relegation-battling rival could be the end of the road for the 44-year-old.
The four changes to his side - Adler, Djourou, Van der Vaart and Müller returning - were expected to power the Red Shorts on to victory. Yet, Hamburg was ponderous and lacking quality across the pitch, while Pal Dardai's side was stingy in defense and showing more confidence in possession after three previous games without defeat.
The most dangerous of their chances in the first half came from outside the box with Zoltan Stieber firing wide twice from the best part of 30 yards out. The Berliners ended the half on the front foot and former HSV player Anis Ben-Hatira saw his shot deflected from the corner of the box.
Hamburg choke late on
Zinnbauer dipped into his substitutes on 63 minutes with the return of Pierre-Michel Lasogga adding a second threat to the attack alongside Ivica Olic. However, with just 16 goals this season - the lowest in the Bundesliga - the northern Germans required much more than some tinkering with personnel.
Neither Lasogga nor Olic could punish John Anthony Brooks for his blunder on 68 minutes, a chance that was eventually cut out by Fabian Lustenberger. In the 79th minute, Olic turned on the edge of the box, but fired from a tight angle into the side-netting.
With 10 minutes to go, Cleber was shown his second yellow card and four minutes later, the Berliners had the ball in the net from a set-piece. Marvin Plattenhardt delivered a tantalizing cross with his left-foot and Langkamp headed low from eight yards into the net to secure the three points.
Hamburg chiefs now have a decision to make over Zinnbauer's future - agonizing over changing the coach and looking for a short-term bounce to keep their head above water at the bottom.
But what indeed that next step is for Hamburg - a decision that could be taken over the next few days or the international break - could be season-defining; even history-defining for the northern Germans.