Arsenal boss Unai Emery is sweating it out over his mounting injury list, and Arsenal could be forced into signing a center-back in this winter transfer window. The Spaniard believes the Gunners will require a defensive cover to keep their impressive run going. The Spanish tactician is running short at the back with his options limited after center-back Rob Holding saw his season come to an end with a horrific knee injury last week. To make matters worse, his first choice defenders Sokratis