The Spanish international forward sustained the knock after receiving a hard kick to his side in Saturday's match at Malaga.
The 26-year-old was forced from the game suffering discomfort, and is now a slight doubt for Saturday's clash with Valencia.
Raul will definitely play no part in Real's forthcoming friendly with River Plate - being staged in honour of Real legend Alfredo di Stefano - and will be rested along with colleagues Ronaldo, Iker Casillas and Esteban Cambiasso.
