Mithali Raj opted to field and West Indies were comfortably placed at 69 for one in the 19th over before things fell apart and the current World T20 champions were tottering at 91 for 6.
Deepti (2/27 in 10 overs), Poonam (2/19 in 10 overs) and Harmanpreet (2/42 in 10 overs) shared bulk of the spoils with opener Hayley Mathews being the top-scorer with 43.
Apart from the trio, the other impressive performer was another left-arm spinner Ekta Bisht (1/23 in 10 overs).
The normally economical Jhulan Goswami (0/37 in 6 overs) went for runs as Mathews hit seven boundaries during her 57- ball knock.
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However between overs 20 and 35, West Indies innings went haywire at the County ground -- a venue which was ruled by Sir Vivian Richards during his days for Somerset in county cricket.
If West Indies managed to cross 180, it was due to Fletcher and her 37-run stand with Anisa Mohammed (11).