Ginobili suffered the injury on a rim-rattling dunk in the third quarter against the Houston Rockets on Tuesday night and was soon limping and holding his upper left leg. He remained in the game for a bit before walking off the court and into the locker room at the next timeout.
The 36-year-old Ginobili missed two games earlier this month with a similar hamstring problem. He's averaging 12 points and 4.5 assists this season.
The Spurs have been bitten hard by the injury bug.
Kawhi Leonard suffered a non-displaced fracture in his right hand last week and is expected to miss three to four weeks. He joined starting center Tiago Splitter (shoulder) and former starter Danny Green (hand) on the injured list. Tony Parker has a bruised shin that still limits his mobility.
The Spurs hope to get Splitter back before they leave for their annual rodeo road trip.
"What can I tell you?" coach Gregg Popovich said, according to the San Antonio Express-News. "It is frustrating, but I don't know what we can do about it. We just got to get our other guys to step up and play. You know. They're trying. That's all I can ask of them."
The Associated Press contributed to this report.