Set to chase 123, openers Sidra Ameen and Gull Feroza provided a flying start to the home side, amassing 35 runs in the first five overs.
But their promising start was shortlived as Hayley Matthews dismissed Sidra in the sixth over to break the threatening partnership.
Sidra scored 23 off 17 deliveries, hitting three boundaries.
Her opening partner Feroza, followed her back to the pavilion in the next over after scoring a cautious 13 off 17 deliveries.
Pakistan then lost another wicket Ayesha Zafar was cleaned up by Karishma Ramharack in the 10th over with just 53 runs on the board.
Coming out to bat at No.5, Pakistan captain Nida Dar took charge of the run chase and pulled her side into the hunt with crucial partnerships with Muneeba Ali (18) and Aliya Riaz (12).
Pakistan then needed 19 runs off the last three overs with Dar and Riaz at the crease. However, Karishma Ramharack turned the game on its head as she removed both the set batters and Fatima Sana for a golden duck, yielding a mere two runs in the process.
Dar remained the top scorer for Pakistan with a 24-ball 27, which featured four boundaries.
Later, Tuba Hasan and Najiha Alvi put together a sensational partnership for the eighth wicket and brought Pakistan in touching distance but Shamilia Connell held her nerves in the final over and propelled West Indies women to a thrilling one-run victory.
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Ramharack led the bowling charge for West Indies with 4/15 in her four overs while Matthews, Afy Fletcher, and Qiana Joseph made one scalp each.
West Indies captain Hayley Matthews’ decision to bat first after winning the toss, did not bore fruits as her side could put up a modest total on the board despite gutsy knocks from Qiana Joseph and Stafanie Taylor.
The touring side had a dismal start to their innings as they lost their captain Matthews (0) and wicketkeeper batter Shemaine Campbelle (2) with just 14 runs on the board inside four overs.
Following the early debacle, in-form Taylor joined forces with Joseph and launched a recovery.
The pair batted sensibly and added 55 runs for the third wicket before Tuba Hasan got rid of Taylor to open the floodgates.
Taylor remained a notable run-getter for West Indies, scoring 30 off 32 deliveries with the help of four boundaries.
Joseph soon followed in Taylor’s footsteps and fell victim to Nida Dar in the next over.
She smashed four boundaries and top-scored for West Indies with a 36-ball 34.
Following their back-to-back dismissals, West Indies began to lose wickets at regular intervals before eventually settling for a modest total.
Fatima Sana led the bowling attack for Pakistan women with 3/24, followed by Sadia Iqbal, who bagged two wickets.
Diana Baig, Nida Dar, and Tuba Hasan, on the other hand, made one scalp each.
PLAYING XIs
Pakistan:
Muneeba Ali, Sidra Ameen, Nida Dar (c), Diana Baig, Aliya Riaz, Fatima Sana, Gul Feroza, Najiha Alvi, Tuba Hassan, Sadia Iqbal, Ayesha Zafar.
West Indies:
Hayley Matthews (c), Qiana Joseph, Shemaine Campbelle, Stafanie Taylor, Chedean Nation, Chinelle Henry, Aaliyah Alleyne, Afy Fletcher, Cherry-Ann Fraser, Karishma Ramharack, Shamilia Connell.