Benfica have already concluded a deal for Argentine Lisandro Lopez - not to be confused with the Lyon forward of the same name.
Defender Lopez, 23, has arrived from Argentine outfit Arsenal and is already being touted as Garay's replacement.
"I believe in my own ability and I am ready for everything, even to replace Garay," said Lopez.
"I spent three wonderful years at Arsenal, I take with me very positive things.
"Now I am going to have the chance to improve my career in a European league, and that is going to give me much more experience and the chance to be recalled to the national team.
"I am just 23 years old and everything has happened very fast to me. I have to be calm and keep my feet on the ground."