Michael Harriman looks set for another spell on the sidelines after cracking a rib during Tuesday's FA Cup replay against Cambridge.
It was only Harriman's third start of a season that has been plagued by injury, but he lasted just 40 minutes at the Abbey Stadium.
"I thought Michael started strongly but unfortunately he's cracked a rib and for him that's so disappointing," said manager Jon Brady.
"Every time he gets an opportunity, he picks up a niggle or an injury and it's a tough one for him to take and that's another one on our back-line as well.
"It's a tough moment for him personally and it's not good for us."
On the plus side, fit-again Aaron McGowan replaced Harriman and seemed to come through unscathed while influential midfielder Jack Sowerby appears close to a return.
"Jack had that niggle and we've just tried to protect him," Brady added.
"We're also trying to protect Aaron and give others an opportunity.
"He had to come in tonight and he managed to get through the game, which is one positive for us.
"We'll assess it through the week and hopefully Aaron has come through unscathed."