Samuel is set to join the Spanish giants on July 1 from AS Roma.

Financial terms of the signing were not disclosed but sports daily Marca said on its website Real had secured Samuel for 22 million euros ($26.22 million), beating off competition from Chelsea for the powerful 26-year-old who joined Roma from Argentina's Boca Juniors in 2000.

"We have reached an agreement in principle with Roma and with the player and we can finally announce we've signed a central defender, a priority for us for next season," Real Madrid's sporting director-general Jorge Valdano told Realmadrid.com.