Duncan is recovering from a sprained knee suffered against the Wizards last Sunday. Ginobili has been battling injuries all season, most recently a hamstring strain.
The Spurs continue to plow ahead through the West despite their injuries, sitting atop the conference with a 39-11 record and an 11-game winning streak.
If Duncan is unable to play, expect Boris Diaw to start in his spot.
Duncan, 36, is averaging 17.3 points and 9.7 rebounds this season. Ginobili, 35, is averaging 12.5 points and 4.5 assists.