"Dean's seeing a specialist today but unfortunately he has done his right cruciate, which is the one he did before. There's obviously a long period of rehab for that one," manager Sean Dyche told reporters on Thursday.
"He will definitely be out for the season, but he's come through that once before so he knows the script. It's a blow for him and a blow for us. He's a tough-minded man and knows he's got the full support of everyone here."
Burnley host second-tier side Bristol City in the fourth round of the FA Cup on Saturday before they face Leicester City in the league three days later.
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(Reporting by Shravanth Vijayakumar in Bengaluru,; Editing by Neville Dalton)
