Sri Lankan skipper Dinesh Chandimal declared the Test series which ended in a whitewash by India on Monday to be the worst of his career, after the hosts were brushed aside by an innings and 171 runs.
India defeated Sri Lanka inside three days in the third and final Test, dismissing the beleaguered islanders for 181 during their follow-on in an extended second session in Pallekele.
For Sri Lanka it was their second successive innings defeat and another blow for a side beset by injury woes and leadership changes.
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Chandimal, 27, was appointed Test captain after Angelo Mathews stood down last month in the wake of a humiliating one-day series loss to Zimbabwe.
But the thrashing by India on home soil was a low for the veteran of 39 Test matches.
"Toughest series no doubt in my career," Chandimal told reporters on Monday.
"We were not able to take the games to five days. There have been four-day Tests and three-day Tests. Worst series ever.
"Credit goes to India. They have played outstandingly well in the series... losing within two and half days you cannot give any excuses."
Sri Lanka replied with just 135 in their first innings to India's 487, putting the world's top Test team in firm control as early as day two.
All-rounder Hardik Pandya set up the win with his blistering 96-ball 108, cracking his maiden century in just his third Test appearance.
Sri Lanka, who swept Australia 3-0 at home last year, struggled during this series as key players were ruled out with injuries.
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Bowling mainstay Rangana Herath was absent in the final Test, while injuries kept allrounder Asela Gunaratne and paceman Nuwan Pradeep on the bench.
Chandimal said injuries dogged some of his best players, including Pradeep, Suranga Lakmal, Herath and Gunaratne.
"I would say the main concern is injuries. The Australia series, we had everyone fit," he said.
"(But) I don't want to give excuses. We have to perform better than this."
The two sides now play a limited-overs series, with the first of five one-day internationals on August 20 in Dambulla. They will also play a single Twenty20 match next month.