Hamburg have sacked manager Bruno Labbadia for a second time following their poor start to the new season.
The 50-year-old was re-appointed at the Volksparkstadion in April 2015, five years after an ill-fated 10-month spell in the hotseat.
HSV have claimed just one point from their opening five matches of the new Bundesliga season and have suffered four back-to-back league defeats for the first time since Peter Knabel was sacked and replaced by Labbadia last year.
Explaining the decision, Hamburg director Dietmar Beiersdorfer said: "The step was necessary because of the sporting situation we are in. I am convinced that we need to change our head coach after the disappointing start to the new season in the hope that we can turn things around. After the long preparation period and the games so far, it is clear that our development is well below our expectations.
"On behalf of the whole club I would like to thank Bruno for the job he did here. It will never be forgotten how hard he worked during what was a tough and challenging time."
Former Hoffenheim manager Markus Gisdol has been appointed as Labbadia's replacement on a short-term contract running until the end of the season.