By Katie Catherall Pau Cubarsi was forced to leave the pitch during Barcelona’s Champions League clash with Red Star Belgrade on Wednesday night after suffering a facial injury. The defender was involved in a brutal clash with Uros Spajic during which the Serbian’s boot collided with Cubarsi’s face – leaving him unable to continue. The high challenge saw Spajic receive a yellow card, while the Spanish youngster retreated to the touchline for treatment. Fans were initially worried about the 17-year-old after he nursed several bloody cuts, but Barca manager Hansi Flick was quick to provide a hop…