West Indies defeated west indies by 3 runs in a thrilling match, marking its first win in a make-or-break T20 World Cup clash on Friday.
Nicholas Pooran smashed 40 off 22 balls to lift holders West Indies to 142-7 against Bangladesh.
Bangladesh opted to field after winning the toss and the bowlers responded with quick wickets including Chris Gayle out for four in Sharjah.
Mahedi, Shoriful Islam and Mustafizur Rahman took two wickets each.
Roston Chase scored 39 on his T20 debut and Pooran put on 57 runs for the fifth wicket to give the West Indies impetus in the final few overs.
Former captain Jason Holder hit two sixes in the 20th over and added a five-ball 15 on his return to the team.
Mustafizur Rahman struck first to see the back of Evin Lewis after the left-hander gave away a catch to Mushfiqur Rahim at square leg.
Mahedi then got the big wicket of Gayle with the big-hitter bowled for four after moving back to his opening slot in the batting order.
Mahedi struck again in his next over to send back Shimron Hetmyer for nine as West Indies slipped to a precarious 32-3.
Chase tried to keep West Indies in the hunt of a big total but they kept losing wickets.
The two-time champions suffered a double blow in the 13th over when skipper Kieron Pollard retired hurt with a possible hamstring strain and Andre Russell was run out for nought.
After coming in for a bit of hammering by Pooran, who smashed four sixes, Bangladesh came back with Shoriful taking down Pooran and then Chase on successive balls.
Pollard (14) returned to sign off the innings with a six.
Bangladesh need 143 to win and keep their hopes alive of making the semi-finals from Group 1 led by unbeaten England and Australia.