"I won't be playing Harry against Middlesbrough," said Benitez. "I think it's better for him to train. I want him to recharge this week.
"Harry is working hard and training well. We feel he needs to increase his physical level and he has a special training programme which we've given to him. You won't see the results in a week, but maybe in a month.
"This season he's had muscle problems and when you lose a lot of training it becomes difficult to play to the same level.
"If you play like Harry with a muscle problem for a month then go away with the national team and lose a week's training, you can't change your physical condition.
"If you say: 'I need to lose three kilograms', you lose water not fat. You need two or three weeks to lose fat.
"If you play games you decrease your physical level. You increase it by training. He needs to improve his physical condition and then we will see the best player.
"But if you said to me you have two or three players better than Harry in his position, I would say it's not true. He is one of the best in England. He needs to regain confidence and improve his physical level.
"All the players are tested for different attributes. Some are quicker than others, others have more strength and resistance.
"We give each one a programme to improve. With Harry, we want to improve his resistance level and stamina. If he can improve this, he will make more sprints in a game and be stronger. Then his form will improve."