The former AS Roma midfielder came on for the final 15 minutes of the Reds' 2-1 Carling Cup loss to Arsenal and although Benitez was impressed, he knew that there was much more to come from the 25-year old, who was unlucky not to have been awarded a penalty after an overhead shot seemed to be handled in the area by Arsenal's Philippe Senderos.
"Aquilani said it was a penalty.The worst thing was the defeat and the result," said Benitez.
"But there were positives - and Aquilani was one of those.
"It would have been a perfect start to win the penalty and, when you start doing things well, the fans support you more than if you just play.
"Hopefully, he will be more lucky in the future. He needs to improve his fitness but he can pass in the final third and make a difference to us."
Benitez admitted that Aquilani would not be in the starting line-up against Fulham on the weekend, preferring to err on the side of caution after a lengthy spell on the sidelines with an ankle injury.
"He could be an important player. But we can't push too hard with him. He will not start on Saturday. It is too soon," he added.