Sporting Lisbon reportedly have a major concern over Ousmane Diomande’s form, with the defender wanted by Arsenal. The 20-year-old centre-back exploded onto the scene over the last 12 months, with Diomande going from a relative unknown to one of the most highly sought sought-after players in Europe. With such a rise comes transfer interest, and Arsenal are one of the many clubs reportedly scouting Diomande, who is believed to have a release clause worth £70m. However, according to Record, Sporting have a ‘concern’ over whether clubs will still be interested in Diomande come the summer, with th…