Assistant boss Kevin revealed that Younes Kaboul (groin), Gareth Bale (thigh) and Scott Parker (hamstring) were all doubtful for the fourth round trip to Vicarage Road.
"Younes didn't train on Wednesday," said Kevin. "Scotty and Gareth both had to come out of training early. They all felt slight muscle strains and all three are doubtful."
Kevin added that Sandro and William Gallas both remain out with calf injuries.