I have the same problem at Liverpool but it genarally means i have to play Aquilani or Lucas there but they are pretty rubbish. If you want a quality player then drop Gerrrard into that slot next to Mascherano and then depending on the money you have and what season youre in then you should get Thomas Muller from FC Bayern. Hes extremely good at creating and scoring goals and hes young and can play anywhere in midfield or up-front. But hes expensive but if you want him youll need to get him first season but he is definately worth the price.
Hamsik, Joao Moutinho both perform, if u have a larger budget: Pjanic, Gourcuff or drop Gerrard back and buy someone like Aguero who can play behind the striker