Champions League: Paul Merson names player Arsenal will regret selling

Paul Merson, an Arsenal legend, has identified Gabriel Martinelli as the player whose absence could cost the Gunners in the UEFA Champions League this season. Arsenal will start their campaign with an away match against Napoli, having finished as runners-up last season. Merson believes that selling Martinelli to Al-Hilal could hurt Arsenal's chances of winning the title this year.