Liverpool head into their meeting with Manchester United having lost their last four games - their worst run for 22 years - and with injuries to key players Steven Gerrard and Fernando Torres.
Aquilani, the £20 million Italian midfielder signed in the summer to replace Xabi Alonso, played in a Liverpool shirt for the first time on Wednesday night in the reserves as he continues his recovery from ankle surgery.
But Benitez insists the 25-year-old needs time to settle in even when he is fit enough for the first team - and that is still some time away. He said: "Alberto is intelligent, he likes football and he has been watching our games. He can see the pace is different here and the physical approach. There is a difference between what you see and how you play but when he gets out and feels the atmosphere here, it will be something special for him. When will he play? It depends on how he is physically.
"He has got very good levels of stamina but now he has to improve his sharpness. To get match fitness he needs to play games and what we have to do is analyse carefully which game is the best and how long he will play for. Always with a new player we talk about the problems they have settling down because the Premier League is very quick and it is more physical.
"So for a new player who has been injured, like Alberto, it will be even more difficult. It is a question of keeping him training and when he is fit, we have to support him. We will have to choose the right moments to put him on the pitch. But he is learning all the time and we are looking forward to playing him.''
Aquilani, who signed from Roma, himself admitted he still has some way to go. The Italian told Liverpool's website: "I am happy to have made my debut. It's been a very long time since I last played. Although I only played for 15 minutes it is good for me and my fitness. I know I am not fully fit yet but I hope to be soon.''