Rangana Herath grabbed six wickets in the second innings to become Test cricket's most successful left-arm spinner as Sri Lanka defeated Bangladesh by 259 runs in their first Test at Galle on Saturday.

Herath finished with 6-59, his 23rd five or more wicket haul, which took his tally in Tests to 366 wickets, going past New Zealand's Daniel Vettori, who has 362 wickets to his name.

His exploits helped Sri Lanka dismiss Bangladesh for 197 runs in the second innings in less than two sessions on the fifth day after the visitors resumed play promisingly on 67-0.

"I would say kind of a big achievement, but I must thank every single person who has supported me - the support staff, my family - I want to say thank you to all of them," Herath said about his record.

"Everybody chipped in and I must congratulate everyone because it is a team effort," he said about the victory.

Herath claimed four of the last five wickets that fell in the post-lunch session as Bangladesh were folded in 60.2 overs to hand Sri Lanka a 1-0 lead in the two-Test series.

Off-spinner Dilruwan Perera claimed two wickets in the morning to trigger the collapse in Bangladesh innings before Herath took charge of Sri Lanka's bowling unit.

Bangladesh lost unbeaten-overnight batsman Soumya Sarkar in the second ball of the morning and failed to regroup as they lost wickets at regular intervals.

Soumya got a leading edge off the first ball, which somehow missed a fielder. However, the next ball of medium pace Asela Gunaratne clipped the bails of his off stump to dismiss the left-hander with his overnight score of 53.

Perera then struck in successive overs, trapping Mominul Haque leg-before for five before forcing a catch from Tamim Iqbal to Gunaratne at slip for 19.

Herath delivered further blows when he removed Shakib Al Hasan for eight and handed Mahmudullah a second-ball duck in a space of three balls in one over.

Shakib gloved a catch to Dimuth Karunaratne at leg slip while Mahmudullah was deceived by an arm ball, which hit his back foot, to be adjudged lbw.

Skipper Mushfiqur Rahim and wicketkeeper-batsman Liton Das put 54 runs for the sixth wicket but Sri Lanka wrapped the innings quickly once left-arm spinner Lakshan Sandakan broke the stand.

Mushfiqur fell to Sandakan for 34 runs before Herath removed Liton for 35 runs to expedite the win.

Mushfiqur refused to blame the pitch for their defeat.

"I thought the wicket is still pretty good to bat, it does not look like a day five wicket," he said.

"It came down to how we batted on the final day and the first session was going to be crucial, but we unfortunately lost wickets."

Sri Lanka's Kusal Mendis was named man of the match for his heroic 194 runs in the first innings.

"I am extremely happy about the achievement and thank Rangana Herath and rest of the team for the support," he said.

The second Test, Bangladesh's 100th, will be held in Colombo between March 15-19.