Leeds United captain Richard Naylor has undergone a minor knee operation and will be out of action for up to six weeks.
The 33-year-old has been on the sidelines recently with the problem and, after feeling it again in a reserves match, was booked in for surgery.
With Naylor out of the first-team picture, manager Simon Grayson has decided to act now to make sure he is available if needed in future.
"Richard was feeling it after he came back in the reserves so we felt this was the best thing to do," Grayson told the club's official website.
"He went in at the start of the week. It was a case of tidying things up really, and he'll be out for between four and six weeks."
Meanwhile, Grayson has confirmed there will be no more players joining or leaving ahead of the closure of the loan window.
Leeds loaned out Aidan White and Adam Clayton this week and Grayson is against weakening his fringe options any further.
"There's no-one coming in and no-one going out," he continued.
"Almost everyone in the squad is fit and available. I'm happy with what we have and don't feel the need to look elsewhere.
"George (McCartney) is a player we'd like to keep, but that's something we will look at next week."