Despite the relatively easy win in the Cup, Rooney believes that Fulham at Craven Cottage will be a different task altogether.
"The Cup game was quite comfortable," said the 27-year-old forward.
"But at home, Fulham are a different team. They have got players who can take the ball between the lines because the pitch is not as big and then they can create chances.
"They are down near the bottom so they will be fighting to get one or three points."
Rooney has been in fine form since his return from injury and scored another two goals in the 2-1 win over Southampton on Wednesday night.