MK Dons midfielder Jay O'Shea could be out of action for "a number of weeks" according to boss Karl Robinson.
The 23-year-old suffered an ankle injury against Brentford and is not likely to play until at least next month.
"He's way off unfortunately. It's not as bad as we thought, but it's not one with an overnight fix," Robinson told BBC Three Counties Radio.
Shaun Williams will continue to deputise, with Robinson impressed with how the Irishman has improved in defence.
"I'm really pleased with the way Shaun's come on as a central defender this year," he said.
"We've probably kept most of our clean sheets with him and Gary MacKenzie at centre-half."