Opener Tamim Iqbal’s first century against Sri Lanka put Bangladesh in charge of the first test after three days on Tuesday.
Bangladesh was 318-3, only 79 runs behind Sri Lanka’s 397.
Tamim made 133 off 217 balls before retiring due to muscle cramp during the tea interval.
But Mushfiqur Rahim and Liton Das put on an unbroken 98-run stand to keep Bangladesh in command.
Mushfiqur was 53 not out and 15 runs from becoming the first Bangladeshi to 5,000 test runs. Liton was 54 not out.
“It is confidence, understanding what their game plan is. They executed it beautifully,” Bangladesh batting coach Jamie Siddons said.
“If you noted, there was no big shots in the air, apart from Liton a couple of times. Everyone was super disciplined.”
Bangladesh started the day on 76 without loss, and Tamim on 35. He went after the Sri Lankan bowlers aggressively, hitting Vishwa Fernando for consecutive boundaries in the first two balls he faced.
Fernando, who was hit on the helmet during Sri Lanka’s innings, went for a medical checkup after bowling just four overs and was ruled out of the match.
Tamim and the more restrained Mahmudul Hasan added 81 runs in 28 unblemished overs in the morning to reach lunch at 157 without loss.
Bangladesh’s first opening century stand in more than five years ended moments after lunch on 162 when Mahmudul edged pacer Asitha Fernando behind down the leg side. Mahmudul scored 58 off 142 balls, with nine boundaries.
Sri Lanka had more joy when medium-pacer Kasun Rajitha, Vishwa Fernando’s concussion replacement, had Najmul Hossain caught behind for 1 and bowled captain Mominul Haque for 2.
Mominul has gone for five single-digit figures in a row and 10 in his last 13 innings.
Bangladesh lost three wickets for 22 runs to be 184-3.
But Tamim continued in attack mode and brought up his 10th test century off 162 balls, flicking Asitha for a single through midwicket.
He and Mushfiqur helped Bangladesh regain control.
Tamim was dropped on 114 and reached tea on 133 including 15 boundaries, but the effort in the hot and humid conditions forced him to retire, 19 runs from 5,000 in tests.
Mushfiqur, largely watchful, and Liton Das, the aggressor, continued to wear down the Sri Lanka bowlers with their near-century stand from 35 overs.
Mushfiqur raised his 26th half-century off 125 balls and Liton his 11th off 96.
