An oblique warning about the January transfer window was delivered to the board of La Liga powerhouse Real Madrid tonight.The club’s final crushing of Borussia Dortmund was preceded by as much.Vinícius Jr. proved to be the hero of the show with a hat-trick in the second half of Real Madrid’s raging 5-2 victory on Tuesday.Nevertheless, Los Blancos were in serious difficulty after 45 minutes at the Santiago Bernabéu.This occurred as Donyell Malen and Jamie Bynoe-Gittens’ goals gave Dortmund a 2-0 lead almost immediately.And those working in the capital of Spain should have been paying close attention as they made their way to the same conclusion.Although Carlo Ancelotti’s team did not celebrate either of Dortmund’s goals as a squad, one player in particular was horribly taken off guard for both.The person in question? Vázquez Lucas.Due to Dani Carvajal’s unavailability, Vázquez was requested to play right-back once more this evening.And while though the Spaniard scored the game’s third goal, which was crucial to Real Madrid’s ultimate comeback, Vázquez’s defensive shortcomings were also made clear to everyone.The 33-year-old has long performed brilliantly for Ancelotti’s team when needed at full-back.However, it is still true that Vázquez is not a defender. He is a winger masquerading as one, which is a commendable sacrifice.In terms of the outcome tonight, Real Madrid did not suffer from his lack of awareness or defensive acumen.Over the course of a lengthy season, though, with Carvajal permanently out, it will eventually, probably during a meeting with another elite team.Florentino Pérez and company must thus take note: the Spanish champions’ squad is in dire need of defensive reinforcements, and they should be given top priority when the January transfer window opens.