The Senegal star insists they can play together.
He told the London Evening Standard: "When he came on the pitch against City he helped me a lot. We caused them problems so I think we could play together.
"We combined against Brentford earlier in the competition, too, so I don't believe it would be a problem for us. Most of the time we have to fight against the two central defenders on our own. If you have an extra body there, it makes it easier.
"This is also very important in football, to be able to control the game. I would understand if Fernando wants to start against Liverpool. We're not making the decision but I would understand if he does."