Kumar Sangakkara became the second batsman in history to score a triple-century and a hundred in the same match as Sri Lanka pressed for victory in the second Test against Bangladesh in Chittagong on Friday.
The tourists, who led by 161 runs on the first innings, declared their second knock at 4-305 in the post-tea session of the fourth day's play at the Zahur Ahmed Chowdhury stadium.
Bangladesh, set an improbable target of 467 to record a series-levelling win, were 0-12 at stumps with Tamim Iqbal on seven and Shamsur Rahman on four.
Sri Lanka will begin the final day needing 10 wickets to sweep the two-match series, while Bangladesh require another 455 runs in a minimum of 90 overs.
Left-handed Sangakkara followed his 319 in the first innings with 105 in the second, joining Englishman Graham Gooch as the only batsmen to achieve the rare feat.
Gooch made 333 and 123 against India at Lord's in 1990.
Sangakkara, with 34 three-figure knocks already under his belt, added one more to the tally with a six off Sohag Gazi after tea, but was bowled off the next delivery.
Dinesh Chandimal remained unbeaten on 100, having shared a fourth-wicket stand of 145 with Sangakkara after Sri Lanka's wobbled at the start.
Earlier, Bangladesh were bowled out for 426 in their first knock within 25 minutes of the start in reply to Sri Lanka's 587.
Spinner Ajantha Mendis finished with 6-99, having claimed both the remaining wickets after Bangladesh resumed the day at 8-409.
Mendis dismissed Mahmudullah with the morning's fourth delivery, forcing a catch to short-leg before the batsman had added to his overnight score of 30.
Al-Amin Hossain was bowled by Mendis for nine, leaving last man Abdur Razzak unbeaten on 11.
Off-spinner Dilruwan Perera supported Mendis with three wickets, while seamer Suranga Lakmal took one.
When Sri Lanka batted a second time, off-spinner Mohammad Mahmudullah dismissed both openers, Dimuth Karunaratne and Kaushal Silva, in his first three overs before lunch to make it 2-49.
Left-handed Karunaratne was snapped up smartly in the slips by Nasir Hossain for 15, while Silva was trapped leg-before for 29.
Shakib Al Hasan then claimed Mahela Jayawardene leg-before for 11 early in the post-lunch session as Sri Lanka slipped to 3-78.
The tourists won the first Test by an innings and 248 runs in Dhaka last week.
