The hosts took a 2-0 lead in the five-match one-day international series with a 68-run win in Chittagong on Sunday.
Openers Tamim Iqbal and Anamul Haque put on a fine opening stand of 158, but the next six wickets fell for just 46 runs before Bangladesh eventually posted 251-7.
Man of the match Mortaza (3-34) and Arafat Sunny (4-29) helped bowl the tourists out for 183, though, leaving Bangladesh on the brink of a series victory.
"It [the win] was 100 per cent professional," he said. "We didn't bat well in the end but the score was good enough.
"We started well with the ball and the spinners as usual bowled well. We lost our momentum after the opening stand but we still ended up with a good total."
Zimbabwe have struggled with the bat in this series and only Solomon Mire showed any prolonged resistance with his maiden ODI half century.
Captain Elton Chigumbura was disappointed that the team were unable to capitalise on Bangladesh's collapse.
"I thought towards the end of the innings we brought it back by taking those wickets and gave ourselves a good chance of chasing it," he said.
"I was happy with the first half but the second half was disappointing, especially losing those three wickets in the first few overs.
"I'm happy for Mire that he scored his maiden fifty. He's a good young player."