Pradeep, who had taken six wickets in the opening Test, had bowled only four balls with the second new ball yesterday and did not take field on Friday.
The fresh injury blow to the hosts means that they have services of just one medium pacer, Dimuth Karunaratne, in the ongoing second Test.
"Nuwan Pradeep's out for one or two months," Karunaratne said at the press-conference after second day's play.
"I started my career as a bowler, not as a batsman, so I can bowl. The thing is there are a lot of bowlers who can bowl faster than 130-135," he said.
"We played only with one pace option, so when they asked me if we need to bowl a few overs with the new ball, I said I could. That's why I bowled a few overs with Chaminda Vaas to see how it goes."
Pradeep could bowl only 17 overs on the opening day. He had left the field complaining of a hamstring niggle.
Sri Lanka is already going through a tough phase due to injuries to their key players. All-rounder Asela Gunaratne was ruled out of the three-match series after he broke his thumb in the Galle Test.
Skipper Dinesh Chandimal also missed the opening Test due to pneumonia and returned for the second Test only after getting a special exemption from the ICC to use his inhaler.
India had defeated Sri Lanka by 304 runs in the first Test
First Published: August 4, 2017, 8:23 PM IST