Former Pescara midfielder Juan Quintero is reportedly a target for European champions Real Madrid.
Tuttomercatoweb cites reports in the Spanish Press, which claim Madrid could go for Quintero if Mateo Kovacic leaves.
However, a deal could be complicated by whether River Plate redeem their option to buy 80 percent of the Colombian’s ownership for €3.7m before Saturday’s deadline.
From that, Porto would be entitled to 20 percent of any sell-on fee, as per the terms of their loan agreement with River for the 25-year-old.
Quintero impressed in his lone season with Pescara during the 2012-13 campaign, despite their relegation to Serie B, while he has also been linked with English sides Tottenham Hotspur and Wolverhampton Wanderers.
The left-footed playmaker would be the second Colombian to join Los Blancos on the back of an eye-catching World Cup after James Rodriguez in 2014.