Brentford duo Harlee Dean and Adam Forshaw have been sent for scans to assess the extent of the injury problems.
Defender Dean and midfield man Forshaw (calf) both missed Saturday's win against Port Vale and haven't trained this week.
Bees boss Mark Warburton confirmed the pair will undergo further tests to discover how long they will be out.
He said: "Harlee and Adam have been sent for scans. We will have a chat with the medical team tomorrow to see where they are."
However, midfield general Jonthan Douglas returned to full training on Tuesday and should be fit for this weekend's trip to Walsall following a spell out with a hamstring strain.