Senderos signed for the Cottagers last week on a Bosman from Arsenal.
But his World Cup could be over after he sustained an ankle injury in the victory over Spain.
The Fulham defender has been ruled out for their remaining two group matches, against Chile and Honduras, and there is some doubt as to whether he will be available should they reach the knockout stage.
"Victim of the same injury as Alex Frei, an ankle sprain, Philippe Senderos is officially out of the two matches against Chile and Honduras," a team statement announced.
"The doctor Cuno Wetzel has left the door open to a return for the defender for a potential last-16 match.
"But by indicating that his injury is more serious than that of Alex Frei, the doctor has ruled out practically any hope."