Chelsea boss Jose Mourinho wants to sign one more player before the end of the summer transfer window.
The Portuguese focused on consolidating the group so far as he replaced striker Didier Drogba with Falcao and goalkeeper Petr Cech with Asmir Begovic.
He is ready to let Filipe Luis and Mohamed Salah leave but will be looking to buy one more defender to strengthen the defensive department.
"I am looking for a defender to finish this balance in our squad and after that we are ready to answer anything that can happen to our players," Mourinho told Sky Sports News HQ.
"If one of our players in a specific position wants to leave, we agree a deal for a player to leave and we have to answer immediately and bring in somebody else.
"At the moment we have balance in the squad and we cannot lose that."