Stylish left-hander Gambhir struck his second one-day international century after captain Rahul Dravid won the all-important toss and elected to bat. India posted a healthy 284 for eight in 49 overs after the game was delayed by 30 minutes due to rain in the morning. Bangladesh, in reply, could only muster 238 for nine as they gave away the series with one more game to go.

Aftab Ahmed ensured that Bangladesh were in the hunt from the start having scored 40 off 41 balls. Typically, Aftab took the game by the scruff of the neck as, for about 45 minutes, he looked to take the game away from the visitors but after he fell while trying to heave off-spinner Ramesh Powar, the run-rate started to climb due to the fall of regular wickets out in the middle.

19-year-old leg-spinner Chawla, making his one-day debut, bowled effectively as he used the lack of pace in the wicket with good variation of flight and spin. He was the best of the Indian bowlers as he took the wickets of Mohammad Ashraful, Habibul Bashar and Mohammad Rafique and only gave away 37 runs in his 10 overs.

"After the last match we thought the extra spinner would be useful. Sreesanth wasn't available for selection because of a sore calf. It was natural to give him (Chawla) a chance," admitted Dravid in the post-match press conference.

"I was confident with the score as I knew that Bangladesh had to bat really well to win but our bowlers kept it tight almost till the end," said Dravid.

His counterpart Bashar stayed at the crease for long for his 43 off 88 balls that included two sixes. But it was a late-order cameo from comeback man Mashrafe Bin Mortaza that stole the show.

He took 26 runs off left-arm spinner Dinesh Mongia, that included four sixes off successive deliveries. Mashrafe carted three of those sixes over long-on and one over mid-wicket, the biggest of the lot, as Bangladesh took their score to a respectable position.

Wicketkeeper batsman Mushfiqur Rahim, who had a terrible day with the gloves, scored 35 in a workmanlike knock that spanned 43 deliveries.

But he needlessly gave his wicket away to Yuvraj Singh, who took two for 40 as did premier fast bowler Zaheer Khan, who took two for 32.

But the total was a little too much for the hosts as they were chasing the game right from the beginning.

Gambhir, who began his innings with a lovely flick through mid-wicket off Mashrafe in the first over, was the more aggressive of the two openers as Virender Sehwag struck a boundary and a six in his 26-ball 21. His innings ended when he holed out to Javed Omar at mid-off off the bowling of left-armer Syed Rasel.

Mashrafe showed glimpses of his brilliance but was evidently half-cooked as he missed the first game due to a back strain.

Mahendra Dhoni was kept at number three but his was an uncharacteristically slow knock as he faced 54 balls to score 36 runs. Gambhir was taking charge at the other end as the two shared 83 runs for the second wicket, the highest partnership of the match.

Yuvraj Singh chipped in with 24 before tamely returning a simple chance to Mohammad Rafique who took three wickets in the day.

In between, Delhi-born Gambhir, who got a life when he was on 95 after Shakib Al Hasan failed to hold on to a return catch, reached his hundred in the 37th over. He fell soon after as he missed a straight Rasel delivery on 101. He faced 113 balls and struck eleven sweetly-timed boundaries.

"It was important to rotate the strike in the middle," said the 25-year-old batsman who is also making a comeback after having been left out of the World Cup side.

"To score a hundred that helps your team win is the most special part," said Gambhir.

Bangladesh struggled in the field as throws from the deep went haywire and there was some elementary mistakes by wicketkeeper Rahim.

Dravid rallied the lower order as he hustled to score 42 off 47 balls but the rest just faded away as veteran left-armer Rafique, along with Mashrafe and fellow left-arm spinner Abdur Razzak pegged back the Indians in the slog overs as they approached 300-plus runs. Razzak and Rasel took two wickets each while Mashrafe got one.