Brazilian midfielder Lucio faces a battle to save his career after picking up a horrific injury in Hertha Berlin's 1-0 defeat to Schalke on Friday night.
The 28-year-old got his foot caught in the Arena AufSchalke pitch and twisted his knee so badly that his cruciate knee ligaments, patella tendon and meniscus were all badly damaged.
He underwent surgery in Austria on Saturday and will not be allowed to return to Germany for five more days.
He needs total rest for the next few days while no precise prognosis over the full recovery time could be given, raising doubts he may never be able to play again.
"Lucio needs enough time to come back without any pressure," explained Hertha club doctor Ulrich Schleicher.
Reports suggest it could be six to nine months before he may even run again, but there are fears he may never recover from such a devastating injury with the whole structure of his knee damaged.