"We can't use that [squad rotation] as an excuse," said the Reds' vice-captain.
"The manager's done it for three years now and we've always done well in the Champions League and been in finals at the end of the season.
"But it's difficult to say what did go wrong. We never played as well as we can and they played very well.
"Of course it puts pressure on us. We haven't put ourselves in a great position. There are two teams above us now and there's a five point difference between ourselves and Marseille so it's important we win our next two home games.
"Everyone was ready beforehand, but they played very well and every single one of their players performed.
"It was probably a combination of us not playing as well as we can and them playing as well as they have for quite a while.
"We are making it tough for ourselves but there are still four games in which we can get enough points.
"Towards the end was probably the only time we put them under pressure.
"I don't know what's going wrong in Europe at the moment, because we're doing well in the league and Carling Cup. It's difficult to put your finger on it.
"But we've got a big game now on Sunday and we want to go out on a win before the international break."