Fulham's pre-season victory over Austrian side ASK Voitsberg on Wednesday evening was marred by an injury to Sean Davis.
The midfield man came on as a second-half substitute but his participation in the match ended after a collision with an opponent.
"He went in for a sliding tackle and twisted his knee," Assistant Manager Steve Kean told Fulham Today.
"At this stage we don't know the extent of the injury but he's going to be assessed by the medical team on Thursday.
"The pitch was a bit greasy after the rain we had earlier and as a result the surface was playing very fast. As Sean went in for a sliding tackle, their player collided with his leading leg and jarred his knee.
"He stood up, was able to put weight on it and jog around but it was too painful to continue so we took him off as a precaution. Hopefully no serious damage has been done. He'll keep his knee elevated and iced tonight - if need be we'll carry out a scan on Thursday."