In-form opener Pathum Nissanka scored an unbeaten 146 as Sri Lanka tightened their grip on the second test against Bangladesh on day two in Colombo on Thursday.
The hosts were 290-2 at stumps, a lead of 43 on the back of Nissanka's sparkling innings off 238 balls.
It follows his career-best score of 187 in the first Test in Galle, which ended in a draw.
Nissanka found an able partner in former skipper Dinesh Chandimal, who scored a fluent 93 before a lapse in judgement saw him lose his wicket minutes before stumps.
The two put on 194 runs together.
"We are in a very good position, tomorrow we have to bat the whole day. We will try to get a lead of 150 to 200," said wicketkeeper Kusal Mendis.
"Shame he missed out on a double hundred in Galle. I hope he does it here," he said of Nissanka.
Frustrated by their inability to break through, Bangladesh resorted to negative lines and spread fields but Chandimal and Nissanka answered with a flurry of reverse sweeps.
Nissanka's opening partner Lahiru Udara was undone for 40 by a Taijul Islam delivery that held its line.
Originally given not out, the decision was overturned after a review.
Earlier, debutant Sonal Dinusha took 3-22 as Sri Lanka bowled out the visitors for 247.
Bangladesh resumed the day on 220-8 and lasted 8.3 overs with overnight batsman Taijul the last man out for 33, caught off Dinusha's left-arm spin.
All-rounder Dinusha, who came in for the retired Angelo Mathews, had made an instant impact by dismissing Mushfiqur Rahim and Litton Das on the opening day.
Fast bowler Asitha Fernando also finished with three wickets after he struck the first blow on Thursday.
Taijul offered some resistance and survived a reprieve on 20 when Kamindu Mendis shelled a tough chance at wide mid-off, denying Fernando his fourth wicket.
The left-hander frustrated the hosts with a gutsy knock during which he copped a few blows to the helmet.
Bangladesh eked out 33 runs for the last two wickets.
Play began 15 minutes early to compensate for overs lost to rain on day one when only 71 of the scheduled 90 overs were possible. T
The winner at Colombo's Sinhalese Sports Club ground will clinch the series after last week's draw.
"Sri Lanka are ahead in the game at the moment, but we know the new ball is due," said Bangladesh coach Phil Simmons.
"We will try to make an impact with the new ball. We know things can happen quickly if we are able to get a couple of wickets with the new ball."
Sri Lanka: Pathum Nissanka, Lahiru Udara, Dinesh Chandimal, Kamindu Mendis, Dhananjaya de Silva (capt), Kusal Mendis, Sonal Dinusha, Tharindu Ratnayake, Vishwa Fernando, Prabath Jayasuriya, Asitha Fernando.
Bangladesh: Shadman Islam, Anamul Haque, Mominul Haque, Najmul Hossain Shanto (capt), Mushfiqur Rahim, Litton Das, Mehidy Hasan Miraz, Nayeem Hasan, Taijul Islam, Ebadot Hossain, Nahid Rana.