#4 Centre-back
With Umtiti injured and Mascherano leaving for China, Barcelona's defence suddenly became wafer thin with only Pique and Vermaelen available to play. The Belgian showed solid performances in the matches he had played in, but his injury record is still the source of concern for the coaching staff making him an unreliable option for the whole season. On the other hand, Pique isn't in his prime focus at the moment, showing poor judgement and sluggishness in recent matches that have cost Barcelona avoidable goals.
A new recruit is extremely needed to fill the gaps and ensure that the squad keeps on showing dominant defensive displays thanks to Umtiti and Ter Stegen's heroics. Ideally, the centre-back should be adept with the ball and able to provide line-breaking passes to the advanced midfielders and attackers. It is the most important trait for a defender to possess in case he's willing to play for the Catalan Giants.