Arsenal striker Viktor Gyokeres has been told to improve his fitness levels to maximise his impact at the Emirates Stadium this season. The Sweden international joined the Gunners in a £63.7million summer transfer from Sporting CP. Gyokeres is currently sidelined with a muscle problem that has ruled him out of Arsenal's previous two fixtures. The injury also meant the striker was unavailable for Sweden duty during this month's international break. New national team boss Graham Potter was forced