Hull City captain Damien Delaney will miss the next three months of the season after damaging ankle ligaments.
The former Cork City and Leicester City centre back discovered the extent of the damage to his leg joint after having exploratory surgery on Monday.
The 25-year-old went over on his ankle in training last week and will now wear a protective boot to help with his recovery for the next six weeks.
Tigers boss Phil Parkinson has expressed disappointment at losing Delaney for up to 12 weeks.
"It's a massive blow for us because he's a very important player but we'll get over it, I'm sure," Parkinson told the Hull Daily Mail.
"He had the operation straight away and stayed in hospital.
"I should imagine that Damien is as disappointed as we all are here to be ruled out for such a long period."