Carlisle skipper Paul Thirlwell is a major doubt for Saturday's home clash with Brentford after suffering a calf injury.
Thirlwell was forced out of last weekend's draw at Walsall and manager Greg Abbott will know how long he will be without the experienced midfielder when he gets scan results later this week.
Abbott will also be without winger Andy Welsh, who faces a six-week injury lay-off after tearing a calf muscle during training last Friday.
But defender Frank Simek could soon give Abbott a boost as he closes in on a return to full training.
The American right-back tore a thigh muscle in the home defeat to Notts County on the opening day of the season, and has been sidelined since, but is expected to rejoin the first-team squad next week.
Striker Paddy Madden, yet to appear this season due to a broken bone in his foot, is hoping to return to full training before the end of the month.