William Saliba's return to full training with Arsenal is a welcome boost for the club, but it also presents a selection dilemma for manager Mikel Arteta. The 25-year-old defender has been out of action since the World Cup, where he suffered a back injury in France's semi-final loss to Spain. Saliba had been managing his back issue throughout last season, but a specialist's advice led to a lengthy rehabilitation period. Despite his absence, Arsenal's defence has remained solid, with summer signing Ezri Konsa forming a formidable partnership with Gabriel Magalhaes. The duo has helped the Gunners boast the league's tightest defence, conceding just five goals in nine games. Saliba's return to fitness will give Arteta some tough choices to make in his backline, particularly with the busy festive schedule looming. The French international's partnership with Gabriel was a key factor in Arsenal's title win last season, and his return will likely see him slot back in alongside his regular partner. However, this may mean disappointing someone, as Ben White and Jurrien Timber have been Arsenal's first-choice right-backs this season. Konsa's impressive performances have made him a valuable asset, and moving him to right-back could give opposition attackers a formidable challenge. Saliba's return also raises questions about the future of young centre-back Cristhian Mosquera, who has seen limited game time this season. With Arteta aiming to defend the title and achieve European success, there will be plenty of opportunities for him to rotate his many options.