Middlesbrough defender Grant Hall could be out for nearly four months with a thigh injury that may require surgery.
The 29-year-old has seen a specialist and might miss "12-16 weeks", according to Boro boss Neil Warnock.
"It's a real blow. I'm absolutely gutted for him. It's a front thigh injury," Warnock told the club website.
"We don't know if he'll need an operation or not. We've had different opinions so we'll have to make a decision on what's best."
Warnock added: "It was quite innocuous. He finished a physical session and just made a side-pass into the goals, but he pulled up holding the front of his thigh.