Brentford's summer signing Scott Hogan is set for a spell on the sidelines.
The 22-year-old forward Hogan, who joined the Sky Bet Championship club from Rochdale, came on as a substitute in the Bees' 2-0 win over Rotherham United on Saturday, but had to go off 15 minutes later with a knee problem.
Brentford's head of medical Neil Greig told the club's website: "Unfortunately Scott's injury on Saturday has proven to be significant and will require some careful management from this point.
"At this stage, the short-term need is to consult with the leading knee specialist in the country and devise a management plan that will see Scott return to full health and fitness in the safest time possible.
"Further information on timescales for the long-term will available following this week's consultations.
"Scott has demonstrated a first-class attitude during his short period with the lub.
"This will stand him in good stead whilst recovering from this setback and I have no doubt will see him return to fitness."