Ginobili was hurt with 9:46 left in the first quarter when he slid to the floor near the free throw line and the Suns' Grant Hill fell on top of him.
He went to the locker room holding the arm and grimacing in pain. The Spurs said X-rays were negative for a more serious injury.
He is scheduled to have an MRI on Thursday in San Antonio.
Ginobili missed two games this season, only one with an injury. With San Antonio already clinching the best record in the West, Ginobili, Tim Duncan and Tony Parker sat out the Spurs' 102-93 loss to the Lakers in Los Angeles on Tuesday night.
All three were back in the lineup against Phoenix.