#3: Leonardo Bonucci (AC Milan)
Third and finally, Leonardo Bonucci would help to strengthen Real - in a different sense to the aforementioned duo. Real's backline have become too predictable and the Italian has proved his ability at Juventus prior to his summer move to Milan.
Of course, it's impossible to ignore his loss of form since arriving at Milan. He himself has been honest with his assessment of the season thus far, saying he has struggled both with the mental side of things following a surprise move, as well as his physical condition too.
Despite saying things would get better earlier this month, it's evident that he is best playing among players at the highest level - Milan, as ambitious as they are, are not yet that good and playing in a two-man defensive partnership does not suit Bonucci in the current circumstances.
As a result, if Real's interest in the 30-year-old is serious, Zidane would look to alter the formation while introducing Bonucci in the centre of defence. Conceding goals more frequently than Real should do, has lead to them dropping more points.
The inclusion of another defensive-minded player within the backline will see a midfielder sacrificed, potentially Mateo Kovavcic or Isco - depending on the opposition.
Bonucci has developed a reputation for reliability and quality for consecutive seasons in Italy and although the last few months have been tough, class is permanent. Unlike both Dybala and Aguero, he would be eligible to compete in the Champions League knockout stages - having represented Milan in the Europa League before Christmas.