The wing signing from Wolfsburg is carrying a thigh injury.
"I've grown up in Germany, that's where I have played all my football," he told fulhamfc.com. "But for as long as I can remember it has been my dream to play in the English top flight. Wonderful football is played in the Premier League and on top of that it is fast and very aggressive.
"This league is the toughest in the world, so with that comes many challenges. This is a huge step for me, but I'm confident of furthering my career here. I know that I will have to work extremely hard in making sure that happens, but I have everything I need here at Fulham.
"It's a good time to be part of this Club, I know that. In fact, I have to pinch myself to believe that I'm actually here. It's a fantastic feeling - it's a dream come true.
"Of course, I would like to be showing what I can do from the start, but unfortunately at the moment I'm not fully fit. It's not a serious injury, but you can't rush back - no matter how desperate I am to pull on the Fulham shirt."