Interim coach Luis Castro has revealed that the 35-year-old Brazilian will face an extended spell on the sidelines due to a torn Achilles tendon.
Helton was withdrawn 62 minutes into the 1-0 defeat to Sporting Lisbon.
It was Luis Castro’s first taste of defeat and the interim coach later confirmed that his keeper’s season appears to have come to a premature end.
“Helton’s injury is serious. I think it is a complete rupture of ligaments. I’m no doctor but it is natural (to think) it should have finished his season,” he told Sport TV.
“The injury to Helton and the game we had on Thursday were factors that limited us a little,” he added, referring to his side’s Europa League victory over Napoli on Thursday.
