Real Madrid scouts have been monitoring the situation of Porto centre-back Eder Militao, according to Marca.
The Brazilian joined the Primeira Liga champions last summer from Sao Paulo and has excelled during his debut season in Portugal.
Porto are asking €40 million for the highly-rated defender who has four years remaining on his contract at Estadio do Dragao.
Los Blancos may not be willing to match that figure, which puts Manchester United in pole position to secure his services next summer.
