Mitchell Starc held his nerve at the death to guide Australia to their maiden win of the T20I Series by four runs after the West Indies almost blasted their way to victory from an improbable position on Wednesday.

Chasing 189-6, the West Indies needed 57 from 24 balls with five wickets left after Mitch Marsh took two wickets in an over, before fireworks from Fabian Allen (29 from 14) and Andre Russell (22* from 13) turned the game on its head in St Lucia.

The pair combined for four sixes from five balls in the penultimate over from Riley Meredith, needing 11 off the final over but Starc sent down five dot balls to Russell in the last to earn Australia a win which makes the series 3-1.

Australia captain Aaron Finch had won the toss and elected to bat, starting strongly with the skipper making 53 from 37 balls alongside Mitch, who top scored with 75 from 44 deliveries, in a 114-run stand.

The tourists stumbled in the middle order again, losing 40-5 with Hayden Walsh taking three wickets, before some late hitting from Dan Christian and Starc lifted them to a strong total.

The West Indies flew out of the blocks in their pursuit with Lendl Simmons posting 72 from 48 before the outstanding Marsh (24-3) dismissed him, along with Nicholas Pooran in quick succession.

All seemed lost for the hosts at 132-5 but Allen and Russell offered hope, before Starc's clutch final over.

Fireworks! #WIvAUS #MissionMaroon pic.twitter.com/ofDaT40Xdn

— Windies Cricket (@windiescricket) July 15, 2021

FULL FAITH IN CLUTCH STARC

Starc had figures of 40-0 and 49-0 in the opening two T20Is but has responded as top players do, claiming 15-1 in the third T20I before Wednesday's clutch final six balls.

The big left-hand quick finished with 37-0 from his four overs on Wednesday, which on paper does not look like anything special but he bowled 13 dot balls overall, including five in the final over with the match on the line.

Starc showed confidence and an ability to execute under pressure with his five final-over dot balls, when the West Indies only needed 11 runs to win.

Starc was bowling to big-hitting West Indian Russell too, who has an arsenal of shots better than most in the shortest format.

Finch said: "We knew if Mitchell Starc executes he's as good as anyone in the world. Lot of faith in him."

Under-rated spinner Adam Zampa was excellent too, with 20-2 from his four overs including 13 dots.

MARSH SHOWCASES REVERED ALL-ROUND TALENT

Mitch Marsh has long divided opinions in Australia, as a son of a gun with prodigious talent who has been afforded too many opportunities.

But the all-rounder showcased why the Australian selectors have long persisted with him, scoring 75 from 44 balls, as well as taking three crucial wickets.

Marsh also smashed four fours and six sixes in his knock. Australia only managed four other maximums throughout their 20 overs.

In fact, the Aussies had only managed 11 sixes in the previous three T20Is, with Marsh hitting three of them, so he offered unmatched power within the ranks.

Finch added: "The way Mitch got away to flier allowed me to sit back."