Melvyn Lorenzen will miss the first three weeks of Werder Bremen's preseason training after being attacked on his own doorstep on Saturday night.
The Bundesliga club released a statement on Sunday confirming the attack by unidentified individuals on Lorenzen, 21, outside his own home, which left the winger with facial injuries.
Lorenzen was taken to hospital and has been told he will be unable to train for three weeks. His attackers escaped before the police arrived.
"Of course we are shocked by such an incident and we hope it gets resolved quickly," Werder Bremen's director of sport Frank Baumann said.
Baumann on #Lorenzen: The incident happened in front of his house last night. There was some disturbance and provocation. #Werder
- SV Werder Bremen EN (@werderbremen_en) July 10, 2016
"We are going to give Melvyn our full support. We hope that he makes a full recovery from this incident very quickly and joins us back in the team."
Lorenzen was born in London to a Ugandan father and German mother and made his debut for the Uganda national team in May.
He joined Bremen in 2013 from Holstein Kiel, made his first-team debut for Bremen in October 2013 and has totalled 14 appearances for the Bundesliga club.