Replying to England's 356, Bangladesh closed on 186 for 9, still 170 runs behind and needing another 21 to avoid the follow-on.
The Bangladesh total would have been even more modest but for the efforts of Rokon, who scored 73 and shared in a 70-run partnership for the fifth wicket with Khaled Mashud (30) which lifted the side from a shaky 54 for 4. Eventually he became one of James Kirtley's four scalps when he was caught by Paul Franks.
Both Chris Schofield and Michael Davies tested the pair with clever variations in their bowling on a pitch offering appreciable turn, and Mashud was caught at slip by Vikram Solanki pushing out at the Lancashire leg-spinner.
Davies, the Northamptonshire slow left-armer, found success when he changed to bowling over the wicket, pushing his first ball across Mushfiqur Rahman, who edged to wicketkeeper Rob Turner. Davies struck again in his next over, producing a ball which turned and lifted to Enamul Hoque, who fended it off to Ian Ward at short leg.
Kirtley struck when he trapped Shabbir Khan lbw, but the last-wicket pair held out until bad light stopped play.
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