Matty James is set to spend between six and nine months of the sidelines after it was confirmed the Leicester City man has suffered a ruptured anterior cruciate ligament.
The midfielder was taken from the field on a stretcher during last Saturday's 2-0 Premier League victory over Southampton.
James subsequently went for a scan and he have surgery on Tuesday ahead of starting his lengthy rehabilitation.
"It's disappointing for Matty, who has been among our most consistent performers in the last three seasons and is an enormously popular member of the squad," Leicester manager Nigel Pearson told the club's official website.
"Recovering from long-term injury is as much of a mental challenge as it is a physical one and, if the positive attitude Matty has shown this week is anything to go by, we can expect him to come back as strong as ever."
