Hamburg have signed promising Turkish youth international Hakan Calhanoglu from German third-tier side Karlsruhe in a £2.1million deal.
The attacking midfielder, 18, has agreed a deal until 2016, but will remain with recently-relegated Karlsruhe until the end of the 2012-13 season.
Karlsruhe general manager Oliver Kreuzer confirmed the deal for Calhanoglu, who has scored three goals in five games already this season, has been completed.
"Hamburg will be able to rely on one of the most promising talents in the German game from next summer," said Kreuzer.
"And we are very happy to be able to further rely on one of the key players of our first-team [for the rest of the season].
"Hakan is an important first-team player for us."