Pollard struck five fours and eight sixes in his 74-ball innings and Darren Bravo gathered 51 from 108 balls, as the Windies, sent in to bat on a hard, easy-paced pitch, were dismissed for 217 in 48 overs at the Sher-e-Bangla Stadium.
Roach collected 5-56 from nine overs – his third haul of five wickets or more in an ODI – but Bangladesh’s batsmen gradually chipped away at the target to clinch their first ODI series victory over West Indies on home soil before a crowd of 24,034, including Prime Minister Sheikh Hasina.
The victory was formalised with 36 balls remaining, when a delivery from Andre Russell was slashed to third man for four Nasir Hossain.
Confusion had reigned, when a delivery from Russell had been driven over cover by Nasir for what would have been the winning run, but Elias Sunny failed to run to the other end to complete the run, thinking the ball would runaway to the boundary for four.
Veerasammy Permaul returned the ball from deep cover and Kieran Powell broke the stumps at the bowler’s end, as Windies captain Darren Sammy and other players protested that the run had not been completed, forcing umpires Enamul Haque of Bangladesh and Ranmore Martinesz of Sri Lanka to consult with the TV Replay umpire to confirm.
The result meant that the Caribbean side lost the series 2-3, after rebounding from losses in the first two ODIs at the Sheikh Abu Naser Stadium in the south-western city of Khulna to win the third ODI this past Wednesday by four wickets at this venue, where they also won the fourth ODI on Friday by 75 runs.
The West Indies batting again crumbled and they crashed to 17 for three in the eighth over, after Kieran Powell, Marlon Samuels and Chris Gayle all fell cheaply.
Pollard came to the crease and added some beef to the total, imposing himself with some lofty blows to put on 132 for the fourth wicket with compatriot Bravo.
He reached his 50 from just 49 balls with a straight six off Sunny and celebrated the landmark with a pull for his seventh six off the next delivery from the same bowler.
Just when it appeared that he and Bravo would seize control, Pollard was bowled essaying a loose drive at part-time left-arm spinner Mominul Haque in the 32nd over.
Bravo reached his 50 from 102 balls with a deuce to deep mid-wicket, but he was part of the wash, as the Windies lost their last seven wickets for 68 in just under 100 deliveries.
Roach gave West Indies a bright start to their defence, when he bowled Tamim Iqbal for eight and had Anamul Haque caught at gully for a duck.
The Windies fast bowler set Bangladesh further back, when Jahurul Islam was caught behind for 10, leaving the home team on 30 for three.
The visitors met resistance however, from Mahmudullah, whose 48 was the top score and helped earned him the Man-of-the-Match award, and Bangladesh captain Mushfiqur Rahim with 44 in the form a 91-run, fourth-wicket stand before off-spinner Sunil Narine bowled them both in the space of 21 deliveries, leaving Bangladesh 133 for five.
Any chances West Indies had evaporated, when Nasir joined Mominul Haque and they added 53 for the sixth wicket.
When Narine trapped Mominul in the 39th over, Bangladesh needed just 32 for victory, and though Roach scalped Sohag Gazi and Abdur Razzak in the closing overs, the result was never in doubt.
WEST INDIES (maximum 50 overs)
K. Powell st Mushfiqur Rahim b Sohag Gazi 11
C. Gayle c Nasir Hossain b Shafiul Islam 2
M. Samuels run out 1
D. Bravo c Mominul Haque b Mahmudullah 51
K. Pollard b Mominul Haque 85
*D. Sammy c Jahurul Islam b Mominul Haque 2
+D. Thomas c wkpr Mushfiqur Rahim b Shafiul Islam 25
A. Russell lbw b Mahmudullah 0
V. Permaul run out 10
S. Narine not out 7
K. Roach lbw b Shafiul Islam 0
Extras (lb5, w18) 23
TOTAL (all out, 48 overs) 217
Fall of wickets: 1-16 (Powell, 2.3 overs); 2-17 (Samuels, 5.2); 3-17 (Gayle, 7.2); 4-149 (Pollard, 31.5); 5-151 (Sammy, 33.1); 6-188 (Bravo, 40.1); 7-188 (Russell, 40.5); 8-204 (Permaul, 44.6); 9-217 (Thomas, 47.4)
Bowling: Sohag Gazi 10-2-32-1 (w7); Shafiul Islam 9-4-31-3; Elias Sunny 8-0-58-0; Abdur Razzak 9-1-39-0 (w2); Mahmudullah 10-1-38-2 (w6); Mominul Haque 2-0-14-2 (w3)
BANGLADESH (target: 218 off 50 overs)
Tamim Iqbal b Roach 8
Anamul Haque c Pollard b Roach 0
Jahurul Islam c wkpr Thomas b Roach 10
*+Mushfiqur Rahim b Narine 44
Mahmudullah b Narine 48
Nasir Hossain not out 39
Mominul Haque lbw b Narine 25
Sohag Gazi c wkpr Thomas b Roach 19
Abdur Razzak lbw b Roach 0
Elias Sunny not out 1
Extras (b3, lb4, w18, nb2) 27
TOTAL (8 wkts, 44 overs) 221
Shafiul Islam did not bat
Fall of wickets: 1-8 (Tamim Iqbal, 2.2 overs); 2-9 (Anamul Haque, 2.6); 3-30 (Jahurul Islam, 8.1); 4-121 (Mahmudullah, 20.5); 5-133 (Mushfiqur Rahim, 24.1); 6-186 (Mominul Haque, 38.1); 7-214 (Sohag Gazi, 42.4); 8-215 (Abdur Razzak, 42.5)
Bowling: Roach 9-0-56-5 (nb1, w3); Sammy 5-1-23-0 (w6); Russell 10-0-51-0 (w5); Narine 10-1-38-3 (nb1, w4); Permaul 9-0-39-0; Samuels 1-0-7-0.
Result: Bangladesh won by two wickets
Series: Bangladesh won five-match series 3-2
Man-of-the-Match: Mahmudullah (Bangladesh)
Man-of-the-Series: Mushfiqur Rahim (Bangladesh)
Umpires: Enamul Haque (Bangladesh), Ranmore Marti