Coach Gregg Popovich said Thursday before the Spurs played in Detroit that Ginobili is expected to be out for 2-3 weeks.
"It's a stress reaction, not a stress fracture, which is important," Popovich said. "If it had been a stress fracture, there's no way he could have been playing, and certainly not as well as he has been."
Ginobili had X-rays, an MRI and a CT scan, and Popovich said the results were encouraging.
"The new bone is already starting to lay down, which means the healing process is underway," he said. "We're thinking that it will be 2-3 more weeks from tonight."
Ginobili had surgery on his left ankle last summer after the Olympics, forcing him to miss the first 12 games of the season. The current problem caused him to miss Tuesday's loss at New York.
"We'll handle it the same way we did the last time," Popovich said. "Whoever we've got left is going to play. I can't tell you who will get which minutes -- I'm going to do it on the fly."
Ginobili is the third-leading scorer for the Spurs, averaging 16.1 points. The Spurs (35-17) have lost two in a row, but still lead the Southwest Division.