Sunderland defender Dan Ballard will be on the sidelines "for the foreseeable future" having suffered a fractured foot, the club have said.
Ballard was making only his third appearance for the club after joining from Arsenal during the summer.
"It is difficult to put a timescale on it," Black Cats boss Alex Neil told the club's official website.
"We have a few other scans to undertake - and a couple of specialists to see - to fully understand the severity of it, but that process is underway to ensure he then receives the necessary treatment to get him back as soon as we can.