The Spanish striker has put off a hernia operation to help the Reds through the Festive schedule, but the manager needs to make sure he doesn't get injured.
"We know it is difficult for Fernando and we have to do it a different way," said Benitez.
"If he is okay, we can give him time. If he feels something, we have to rest him.
"We have to manage his injury. He could manage a full Christmas programme, but we will see if he can start."