Stuttgart striker Cacau is expected to be out of action for at least three months after tearing his cruciate ligament during a training session with his club on Wednesday.
Cacau, 31, suffered the injury while preparing for Stuttgart's home game against Hamburg on Sunday and will now receive conservative treatment, and wear a special splint as doctors try to avoid having to undergo surgery on his knee,
"This is bitter for us," Stuttgart general manager Fredi Bobic said. "I'm dreadfully sorry for him. We will support in every possible way and hope he can spare himself surgery which would see him sidelined for even longer."
Brazil-born Cacau has won 23 caps for Germany, though he did not make it into Germany's Euro 2012 squad and has not been called up to the team ever since.
He has played five Bundesliga games for Stuttgart this season, scoring one goal in Stuttgarts's 2-2 draw in Bremen.