The French centre-back was close to joining the Sky Blues in January, but a double raid for he and Fernando – who has since moved to the Etihad Stadium – collapsed.
Mangala is currently away at the World Cup, but when he returns City chiefs are ready to push ahead with an official offer to lure him to England.
The 23-year-old has been scouted by the Premier League champions for 18 months, and Manuel Pellegrini is said to be convinced that he’s the right man to partner with Vincent Kompany, despite rumours that Roma’s Mehdi Benatia is the favoured option.
Porto are known for demanding big fees for their stars, and it’s unlikely that Mangala will go for any less than £30m, despite the Portuguese giants having endured a below par 2013/14.
Bitter rivals Manchester United have also been linked with the youngster, but a lack of Champions League football at Old Trafford for next season is thought to have all but ruled them out of the running.