Ganguly sustained the injury while fielding during the Pakistan innings as he dived to stop a scorching off-drive by his counterpart Inzamam-ul-Haq.
He lay on the ground writhing in pain before he was stretchered off.
However, team manager Ratnakar Shetty said the skipper was feeling "enthusiastic" now after undergoing treatment by team physio Andrew Leipus in the dressing room.
"I think he has some pain in the back. We have decided to go in for a test. As of now we don't know how serious the injury is," Shetty said.
"He was very enthusiastic and wanted to go back to the field but he was advised against it," he said.
Ganguly has three days to recover before the first Test which starts in Multan on Sunday.
Shetty said whether Ganguly would be able to play the opening Test would depend on doctor's report.