West Indies need to find a way keep up the momentum rather than just battling to one off victories, coach Phil Simmons said after his side secured a thrilling three-wicket win over Bangladesh in the first test in Chattogram on Sunday.

"Every time you win, it is more important you look at ways to improve. When a team loses, they will try to improve, so we as winners have to do the same. We have to improve in every aspect," Simmons said.

"I am tired of these one wins and then struggling for the next three or four games. We have to make sure we don't go backwards again," he added.

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Bangladesh will be forced to make at least one change with left-arm spinner Shakib Al Hasan ruled out due to a thigh injury. But Simmons insisted that the omission of Bangladesh's leading test wicket taker will not lead to complacency for his team.

"We can't afford to take his absence for granted. It won't be easier for us," he said.

"He is one of the top all-rounders in the world, but they have so many spinners ... they will find someone who can do the job," the former alll-rounder-turned coach added.