Porto have approached Manchester City about re-signing Eliaquim Mangala.
The Frenchman faces being frozen out of City's Champions League and Premier League squads this week.
France Football says Mangala could choose to return to Porto, despite rival interest from AC Milan and Juventus.
The defender spent three years at Porto, which can also offer him Champions League football.
Porto hope to set up a loan deal for Mangala this week.