كتب : وكالات
The club's website revealed that the Brazilian winger will be sidelined for two weeks with a torn abdominal muscle.
The 24-year old player had to leave the pitch after only 14 minutes in Real's thrashing victory over Real Valladolid.
The Real star won't be available for this week-end clash against Real Betis and he'll also be a major doubt for the Gunners trip.
Dutch winger Arjen Robben, who made a rampant comeback against Valladolid after a long-term injury, will replace him.
Meanwhile, Ruud van Nistelrooy and Miguel Torres will return to action with their teammates.
Argentinean full back Gabriel Heinze has also recovered but he is still lacking match fitness.