Liverpool have suffered a double blow ahead of Saturday's trip to Fulham with the news that both Steven Gerrard and Glen Johnson will not make the journey to London.
Gerrard has managed just 25 minutes of action for Liverpool since going off at half-time for England against Ukraine with a groin injury at the start of the month.
The skipper made his return against Lyon in the Champions League but was unable to continue leading to an early exit. Johnson missed the game against the French side and will also not face Roy Hodgson's side due to a thigh strain, despite playing the whole of Sunday's win over Manchester United.
Alberto Aquilani, who made his debut for the Reds in the midweek Carling Cup defeat at Arsenal, will also not be part of the squad after coming down with a virus. Benitez joked: "It is a virus but not swine flu, we haven't got that here yet.''
But Liverpool are concerned over Gerrard's persistent problem and will be monitoring their captain closely in the coming days.
Benitez said: "Gerrard is improving but the next week will be crucial in terms of any decision about what we will do with him. I have talked to him today, he is working with the medical team and his progress is slow, but we will then have to decide what to do if he is not progressing as quickly as we would hope.
"He has had this problem for some time but when he has a lot of games for his club, as well as the national team, it is not easy to give him a rest. We will try to manage this differently in the future but we always have the same problem, that he wants to play in every match.
"And that applies to England as well. It is very positive, it is a fine mentality, but maybe we should be looking at the right way to handle a problem that continues to cause him trouble. I do not believe he will have this problem for the rest of his career but we certainly need to find a solution now. We have a good medical staff, I have confidence we can manage this problem.
"I do not know yet whether Steven will play in Lyon, we must work with him. But it is true there is a problem. We do have an issue if he is not fit for Lyon, it is a crucial time. In three days we will maybe have a better idea.''
Benitez' annoyance with England is barely below the surface when he discusses Gerrard, who has played just 25 minutes since the injury against Ukraine and will miss his third successive match tomorrow.
"Steven picked up this injury while playing for England. He lasted only until half-time of the game (in Ukraine),'' Benitez said. "He rested for two days and then had the same problem in his next training session for England. We rested him for one game and then he lasted just 25 minutes of the next match, against Lyon. Since then he has not been able to train or play.
"We now have to be careful. He is working with the physios and I have talked with the doctor. The decision is to continue with the same treatment for a few days. Then we will see. We do not want to put him under any further risk. He was unable to play against Manchester United and we won but we obviously need Steven to be fit and available.
"He has just been nominated for world player of the year, along with Fernando, and they both deserve it. And it also shows the quality we are missing when they cannot play. We are pleased for them and the club that they are being spoken of at such a level, so it is clear that they are not just any player, they are world class and we miss them. Any team would.''