Stuttgart striker Cacau faces a lengthy spell on the sidelines after injuring his knee at training on Wednesday.
The Germany international picked up the knock during training and underwent a series of tests immediately after leaving the ground.
Cacau has been diagnosed with a tear to the inner as well as the rear cruciate ligament, and by implementing a specially designed brace, the doctors are hoping to be able to avoid a surgical correction.
However, the striker will be out of action for at least three months.
"This is of course bitter for us and I feel really sorry for him," Stuttgart sporting director Fredi Bobic said.
"We will naturally support him in every possible way and hope that surgery won't be necessary as he would then be out for an even longer period."
Cacau, 31, has netted once in five Bundesliga appearances this term.