Hamburg have confirmed the signing of Croatia striker Mladen Petric from Bundesliga rivals Borussia Dortmund.
Forward Mohamed Zidan will head in the other direction with an undisclosed fee.
'We are delighted to have pulled off the transfer of Mladen Petric,' said Hamburg chairman Bernd Hoffmann.
'He has shown his class in the Bundesliga and for his national team.'
Petric is due to link up with his national team for a friendly against Slovenia on Wednesday, and his official presentation as a Hamburg player will now have to wait until Thursday.
But before leaving for international duty, Petric told the Hamburg website how much he is looking forward to joining them.
'I really cannot wait,' he said. 'HSV are one of the biggest clubs in the Bundesliga and are the only ones to have remained in the league since their inception.
'I was already at one of the biggest clubs with Dortmund, but Hamburg are certainly a cut above.'
For Egyptian striker Zidan, a disappointing spell for Hamburg in which he scored just two goals in 21 games comes to an end, giving him the chance to resurrect his career under the coach who got the best out of him during a loan spell at Mainz two years ago.
'I am looking forward to joining the club, and obviously (coach) Jurgen Klopp,' he said.
'I had a great time in Mainz and believe that I can play well for him in Dortmund too.
'Obviously it is a bit of shame that I am leaving Hamburg, but I think the transfer is the right choice for me. I need match practice in order to improve.'