It was Rohit's 89 off 61 balls that took India to a competitive 176 for three in 20 overs and then young Washington Sundar (3/22 in 4 overs) blew away the top-order to help restrict the 'Tigers' to 159 for six in 20 overs.
Bangladesh's inconsistency once again proved to be their bane as they found a target of 177 too hot to handle, having chased 215 in their previous encounter.
Liton Das danced down the track as Washington fired a widish delivery, which he completely missed for Dinesh Karthik to complete an easy stumping.
Soumya Sarkar (1) tried a slog over deep mid-wicket and missed the line completely as Washington angled one into him.
The ever dangerous Tamim Iqbal (27 off 19 balls) started on a promising note, hitting three boundaries and a six off a Shardul Thakur over.
Teenager Washington's flatter trajectory paid him rich dividends as Iqbal was bowled trying to scoop another angular delivery over short fine leg. The left-hander failed to get elevation as it clipped the leg-bail.
The 26 dot balls bowled by the spinner (13 each by Washington and Chahal) proved to be decisive in the end.
Even though Mushfiqur Rahim (72 no off 55 balls) fought well with some big shots, the match as a contest was over when Shardul (1/37 in 4 overs) managed to castle Sabbir Rahaman (27) after 65-run partnership for the fifth wicket.
Shardul could be credited for making a good comeback in his last three overs executing knuckle ball with considerable success.
After a prolonged bad patch starting from the tour of South Africa, the stand-in captain was in his element, starting cautiously before finishing with a flourish as he hit five fours and an equal number of sixes off only 61 balls.
The two veterans of numerous IPL battles, shifted gears in the four overs between 16 to 19, in which India scored 55 runs. The final over was a bit of an anti-climax with Bangladesh's best bowler Rubel Hossain (2/27 in 4 overs) keeping things tight and giving away only four runs.
The turning point was the 18th over bowled by left-arm military medium bowler Abu Hider Rony (0/43 in 4 overs), which fetched India 21 runs.
Rony was hit for three sixes --- two by Rohit and one by Raina, which suddenly propped up India's score that was looking below par at one stage.
Of the sixes hit by the Indian skipper, the standout was a slog sweep off Mustafizur Rahaman. He also punished the slower bowlers -- off-spinner Mehidy Hasan Miraz and left-arm spinner Nazmul Islam -- hitting them for a six each.
When Mustafizur (0/38 in 4 overs), while trying for the slower one, ended up bowling full tosses, Rohit opened the bat face to fetch boundaries in the arc between point and third man.
While Rohit upped the ante in the end, Raina once again played a significant role, hitting five boundaries and two sixes.
He started with a couple of boundaries off Miraz -- his signature slog sweep towards the deep mid-wicket region followed by a lofted shot over long-off. He also hit Mahmudullah over mid-wicket for a boundary while an attempted inside-out lofted shot was edged towards third-man for a boundary.
Raina missed out on a half-century as another attempted flick over deep mid-wicket off Rubel was taken by Soumya Sarkar.
India had their best start of the tournament with Shikhar Dhawan (35 off 27 balls) and Rohit adding 70 in 9.5 overs.
Dhawan hit Mustafizur for a six over long on, picking a slower delivery earlier than expected.
Dhawan was bowled by a yorker from Rubel, which uprooted the middle stump.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)