Militao is on the agenda for those at Real Madrid Transfer Market - LaLiga Santander Would cost 50 million euros

Real Madrid are keeping tabs on Porto centre-back Eder Militao as they consider making a move for the 20-year-old in the summer.

The Brazilian turns 21 this month and despite his young age, Madrid understand that this is a player who could become the fulcrum of their defence for years to come, while he has already attracted interest from the likes of Barcelona, who have confirmed a pre-contract agreement with Jean-Clair Todibo, and Manchester United, who look set to sign Roma's Kostas Manolas.

Militao joined Porto last summer from Sao Paulo for a fee of four million euros, with the Brazilian side retaining a 10 percent sell-on fee; he is the latest gem Porto have found, having had plenty of success down the years with players from South America.

They have made it clear that they are a selling club, too, as shown by their transfer activity last summer with Ricardo Pereira and Diego Dalot joining Leicester City and Manchester United respectively for 25m euros apiece.

Porto and Madrid have a close relationship with plenty of business having been done between the two sides down the years: Pepe and Danilo both arrived at the Santiago Bernabeu from Porto; Casemiro spent one season on loan in Portugal, where he developed significantly as a player; and Iker Casillas joined Porto after leaving Los Blancos in 2015.

If Madrid were to sign Militao, his release clause is 50m euros, though that figure is reduced to 42m euros if he is purchased before 31 January, as various news outlets have reported.

What makes things complicated is Porto's presence in the last 16 of the Champions League, where they will face Roma, as well as their advantageous position in both the Primeira Liga and the Taca de Portugal.

On Tuesday, however, Porto did announce the return of Pepe to the club, where he also reunites with Casillas, and this has led some to wonder whether this is in preparation of Militao potentially leaving, though the leaders of the club ensure that this is a signing that strengthens the side ahead of the decisive phase of the season.

Having started out at Sao Paulo, Militao is a centre-back who stands out for his pace and forceful nature, but most notably his adaptation to European football; he arrived at Porto and became the starting centre-back as he - and the team - performed excellently, with the Brazilian drawing lots of attention from some of Europe's biggest sides.

Madrid have now watched the defender on three occasions, with the rule being to usually watch a player five times before making a definitive judgement, but all of the reports so far have been positive and he is a player that many believe would fit in perfectly at Los Blancos.

Last summer, Julen Lopetegui opted to put faith in Jesus Vallejo, rather than sign another centre-back, but the 22-year-old has been plagued by injuries; so much so that Javi Sanchez has been called upon on multiple occasions this season, though he has now returned to the Castilla side.