Hamburg shocked Dortmund on Saturday, earning a 3-0 victory at the Imtech Arena in Mirko Slomka's first match in charge of HSV.
The hosts entered the match 17th, with the league's worst defensive record, but kept a rare clean sheet as goals from Petr Jiracek, Pierre-Michel Lasogga and Hakan Calhanoglu (a golazo that should not be missed; click here for a replay) sealed three critical points in Hamburg's fight against relegation.
The match was a brilliant rebound for HSV and a real wake-up call for BVB. Click "begin slideshow" for a complete analysis of the major talking points from Saturday's action.
Regardless of how dismal this season has been for relegation candidates Hamburg, the northern club remain a class act and a true institution in the annals of German football history.
The club paid tribute to Hermann Rieger with a moment of silence before Saturday's kick-off; the players locked arms as the home fans displayed a banner reading: "Forever our best man, whom no-one can ever replace. Rest in peace, Hermann!"
Rieger was a celebrated legend of Hamburg who served as the club's physiotherapist. He died on Tuesday.
Hamburg have already disposed of two coaches this season, but the third might be a keeper.
Mirko Slomka took his post five days ago with HS deep in the relegation zone, but his Hamburg side completely turned over a new leaf on Saturday. A team that for months had seemed disinterested, being sorely outrun by their opponents, HSV kept pace (according to the official Bundesliga live ticker) with a BVB side notorious for impressive industry.
Despite their poor form, Hamburg have always had some outstanding quality in their squad. Saturday's result was proof that when they make a concerted effort, they can stand up to the Bundesliga's elite teams.
Dortmund had been in excellent form heading into Saturday's match, but that was nowhere to be seen at the time of kickoff in Hamburg. Barring one or two close calls, the hosts were uncharacteristically resilient in defense. They earned the lead they took into half-time, and their second was no less deserved.
Although all were expected to have some time to prepare for Tuesday's Champions League against Zenit, Mats Hummels (left out of the squad), Marco Reus and Sven Bender (both played 45 minutes) are all short of match practice as they return from injuries. Jurgen Klopp will have to think carefully before he selects his lineup to face Zenit.
Dortmund have played nearly two full seasons without an established, qualified backup for striker Robert Lewandowski, and their most important task in the summer transfer market will be to replace the Bayern-bound attacker. Although they are more likely than not set to sign a newcomer, BVB already have a burgeoning talent in Marvin Ducksch.
The 19-year-old Ducksch had played just 106 minutes in the Bundesliga ahead of Saturday's match, but with 12 goals in 18 appearances for the reserves in the 3. Liga—including a brace in his last outing—Klopp deemed him ready to face Hamburg as a substitute.
Although he failed to score, Ducksch produced two great saves from Rene Adler shortly after his introduction. It was an encouraging performance from the player, who could yet play a significant role for BVB after Lewandowski's departure—or maybe even before.
Judging from his performances this season, it's hard to imagine why Hertha BSC ever loaned Pierre-Michel Lasogga to Hamburg. The 22-year-old striker struggled for form after returning from an ACL tear last spring, but that was to be expected. He'd had half a year of training before this season began and was ready. But the Berlin side loaned him.
Hertha's loss has been Hamburg's gain, as Lasogga has scored 11 goals at a rate of once every 108.4 minutes; the latter figure is a league-best for those who have scored more than three goals. Lasogga assisted Petr Jiracek's opener on Saturday and scored the second with confidence and poise.
Hertha can expect Hamburg to do everything possible to retain Lasogga, and it's possible that other clubs will join the race to sign him. Still 22, he has plenty of room to develop.
Nothing matters more than the present in football; a team should only focus on the next game. The past is of little value, and the future beyond the next game is still far off. Dortmund perhaps paid the price of looking towards Tuesday's clash with Zenit rather than focusing on Hamburg on Saturday and paid the price in a brutal defeat.
Robert Lewandowski was utterly impotent, and Nuri Sahin and Sven Bender (prior to his substitution at halftime) offered little fight in midfield as HSV counterattacked again and again.
Just as HSV showed many times this season, that complacency begets disappointment, so did Dortmund learn a similar lesson on Saturday. They will have to dig deep to rebound from their most recent disappointment if they are to get the better of Zenit in three days' time.