Benitez insisted: "To bring in a big, big name, you often have to change everything. It was the same situation when we brought in Robbie Keane.
"People were saying 'but Steven Gerrard and Torres are doing really well,' even though in the end, we needed to change things because they were injured.
"We have signed the players we needed and I don't think we are short in attack. David Ngog is a player with quality, hopefully he can bring something.
"On Wednesday Ryan Babel was doing really well for Holland and don't forget he's a striker. Dirk Kuyt is another and so is Andriy Voronin. We have to adapt to our situation and needed to improve in other areas."