Coach Thorsten Fink was fired by Hamburg on Tuesday just three days after his side were hammered 6-2 by Bundesliga leaders Borussia Dortmund.
"After the recent developments, we concluded that it was inevitable," said director of sport Oliver Kreuzer at a press conference.
Fink's defence was cut to ribbons on Saturday at Dortmund as the Champions League finalists scored four goals in 16 second-half minutes in a horror show for the Hamburg board.
"It was a difficult decision to take for everyone involved, but the reasons are obvious. It came down to the sporting future of Hamburg," said chairman Carl-Edgar Jarchow.
Hamburg are 15th in the league after five games, but more worryingly they have conceded 15 goals -- 11 of which came in two games after Hoffenheim also won 5-1 at Hamburg last month.
Having taken charge of Hamburg in October 2011, Fink's side has a history of capitulating having been demolished 9-2 at last season's champions Bayern Munich in March.
"I'm proud to have been here two years, I have coached a great club," Fink told Hamburg radio station NDR 90.3.
"This team can still reach their goals, albeit with a different coach."
Fink is the second Bundesliga coach to be sacked just five games into the new season after Bruno Labbadia was dismissed by VfB Stuttgart.
For Hamburg's next game at home to Werder Bremen on Saturday, reserve team coach Rodolfo Esteban Cardoso and Otto Addo, who coaches the youth team, will be in charge on a caretaker basis.
"We are now looking vigorously for a successor to Thorsten," said Kreuzer.
"I can't say yet when we will be able to present him. It could happen quickly, but it may take a couple of days."
Former Hamburg player Markus Babbel, former St Pauli coach Holger Stanislawski and Franco Foda, the former Kaiserslautern coach have all been linked to the job.
Felix Magath, who won the 1983 European Cup with Hamburg and coached both Bayern Munich and VfL Wolfsburg to the Bundesliga title has ruled himself out of the running.
"I am not available to coach Hamburg," the 60-year-old Magath told Wednesday's edition of Bild, before taking a dig at Hamburg's supervisory board boss Manfred Ertel and Jarchow.
"In May, Ertel and Jarchow said that Fink was the right man for HSV," said Magath.
"And now he is no longer there? I can only be surprised."
Hamburg captain Rafael van der Vaart was also surprised by the timing, just four days before the north German derby.
"I am totally shocked," the Holland international told German daily Bild.
"I didn't think it was possible, I thought the coach would be on the bench for the Werder game.
"It was my rock-solid conviction. I don't really understand the timing.
"As a team, we have to shoulder some of the responsibility.
"Our recent heavy defeats have cost the coach his job."