The pair broke down during Saturday's 1-1 draw with Wolves.
Bruce would not be drawn on the severity of the pair's issues, telling Sky Sports: "It's too early [to say] but for someone like Micky [Almiron] to come off and be in the state he's in, we fear the worst.
"We could do with a little bit more luck in the injury situation we're picking up, but we have to get on with it.
"For the first half an hour, until unfortunately Micky [Almiron] picked up his injury, we were excellent.
"We have created two, three, four big opportunities and at this level, to be brutally honest, you have to take them. We're a bit disappointed with that and, of course, the injuries again have disrupted us badly."