While Thirimanne is effectively a replacement for the injured Asela Gunaratne, Sandakan's inclusion is a sign Sri Lanka are considering a stronger spin-bowling attack for the SSC Test. He is the fourth frontline spinner in contention for a spot in the XI, in addition to Rangana Herath, Dilruwan Perera and Malinda Pushpakumara. Sri Lanka's attack was found wanting in Galle, where India mounted 840 at a run rate of 4.5, for the loss of only 13 wickets.
The match will also see the return of captain Dinesh Chandimal, who had missed the first game due to pneumonia.
Thirimanne had been a fixture in Sri Lanka's middle order between 2013 and 2016, but had been dropped due to an extended run of poor form. His domestic form has been largely good since, though he was not among the top scorers in this year's Premier League Tournament. He did, however, score 59 in India's warm-up match in Colombo, last month.
Sandakan's form has also been mixed. He had taken four wickets in Sri Lanka's ODI victory over Zimbabwe in Galle, but had two modest outings after that, and was dropped for the deciding ODI of the series. In five Tests so far, Sandakan has 15 wickets at an average of 31.93, though several chances have gone down off his bowling.
Lakmal had not played in the first Test, but was said to have had back trouble even during the Zimbabwe tour that preceded India's arrival. With his exit, Nuwan Pradeep, Vishwa Fernando and Lahiru Kumara are the remaining frontline quicks in the squad.
Sri Lanka squad for the SSC Test: Dinesh Chandimal (capt.), Angelo Mathews, Upul Tharanga, Dimuth Karunaratne, Niroshan Dickwella, Kusal Mendis, Dhananjaya de Silva, Danushka Gunathilaka, Lahiru Kumara, Vishwa Fernando, Nuwan Pradeep, Rangana Herath, Dilruwan Perera, Malinda Pushpakumara, Lakshan Sandakan, Lahiru Thirimanne