Fulham caretaker boss Scott Parker says injury kept Aleksandar Mitrovic out of defeat to Manchester City.
Parker admits playing for Serbia aggravated the issue.
He explained, "He has been struggling for a few weeks with an ongoing issue, he played for Serbia in a tough game with Portugal and came back and he didn't have a chance today.
"Whether we can get him right for Tuesday will be on a day to day basis. We'll try get some treatment into him but I coudn't make a call for Tuesday. He has something wrong with his stomach."