Nolito has declared he wants to leave City this summer and has mentioned interest from Sevilla and former club Celta Vigo.
“When we talk about top players, we can not say things are done, but we are advancing with some players and one of them is Nolito,” he told Radio Sevilla.
“We are getting into the position so he can play with Sevilla.”
City paid Celta Vigo 18 million euros for the player just last summer, so Castro understands the money involved in a deal for a player of this kind of stature.
The Sevilla chief is also not ruling out a deal for Stevan Jovetic, after a successful loan spell from Inter last campaign.
An approach has already been rejected, however he claims deals will be done before July 3, which is the scheduled date for a return to work.