Panathinaikos have completed the signing of Marcus Berg and the striker could reportedly be followed out of Hamburg by Michael Mancienne, Slobodan Rajkovic and Paul Scharner.
Berg has signed a four-year contract with Panathinaikos and has cost an undisclosed fee after becoming the Greek club's third summer signing.
The Sweden international joined Hamburg in 2009 from Groningen, but he struggled to make a lasting impact after scoring five goals in 43 appearances.
Hamburg are now likely to offload further players after general manager Oliver Kreuzer confirmed the priority is to bring in a new striker.
"We are in no hurry and we are not feeling any big pressure, but we are out to sign a new striker," Kreuzer told BILD. "Therefore, it is necessary to keep on selling.
"The most important thing in this matter is that those players are leaving our club."
Reports suggest that former Chelsea duo Mancienne and Rajkovic will be allowed to move on, despite having two years left on their contracts.
The versatile Scharner spent the second half of last season on loan at former club Wigan and the Austrian has a further year to run on his Hamburg deal.