"I'm disappointed because Gerrard will have an operation tomorrow," said Rafael Benitez.
"He has a groin problem. We knew it could be like this and I was surprised when I was reading some of the newspapers saying he has to play and has to start. Now he will have an operation and will be out for 10-15 days.
"It isn't too long but he needs to have it because he has been having pain with it. When he went with the national team we knew he had a problem and in the first-leg too.
"I was talking with the doctor yesterday and today we talked with him [Gerrard]. He said he would play with pain and after it he would have an operation.
"He knew he had to keep going tonight and did so because he knew he was having it tomorrow."