Though there is no injury to Herath as such, he has had a heavy workload over the past three weeks, in which he bowled 71.1 overs in the one-off Test against Zimbabwe, as well as a combined 91 overs in the two Tests against India.
Considering his age, and the fact that Sri Lanka will have to play a Test series against Pakistan over the next two months, the selectors have made the decision to leave him out.
"This is where our player management comes in, because we don't want to break anyone," SLC cricket manager Asanka Gurusinha said. "We made the call not to risk Herath because he's also bowled close to 200 overs in the three Tests. That's a lot for his body." Herath also confirmed he will stay in Colombo and receive treatment, rather than traveling to Kandy with the team.
Though he has had a modest series against India so far, Sri Lanka's attack will nevertheless be significantly weaker in his absence. He was the best of their bowlers at the SSC, taking 4 for 154, and had also taken 11 wickets in the difficult victory against Zimbabwe at Khettarama. Dilruwan Perera will now be the senior spinner, with left-arm spinner Malinda Pushpakumara and left-arm wristspinner Lakshan Sandakan also in the squad.
Herath is the fourth Sri Lanka player to become unavailable during the India series, after both Asela Gunaratne and Pradeep picked up injuries in the first and second Tests respectively, and Suranga Lakmal was ruled out by a back complaint. Herath is not in the habit of missing Tests, however. The last Sri Lanka match he missed had come more than two years ago - against Pakistan in July 2015 - and that was because he was dropped from the XI. The last Test for which he was unavailable was the 2014 Boxing Day Test against New Zealand in Christchurch, when he was nursing a leg injury, and also attended the birth of his second child.
The Pallekele Test is scheduled to begin from August 12. It is, however, a dead rubber, with India having already won the series 2-0.