West Indies fought back to secure an extraordinary victory by 18 runs in the opening match of the T20 series against Australia having been behind the game for large periods at the Darren Sammy National Stadium in St Lucia tonight.The visitors contrived to lose their last six wickets for 19 runs against Obed McCoy and Hayden Walsh Jr having needed less than five an over in the second half of the chase.McCoy, who was impressive in the recent series against South Africa, confounded Australia’s lower order with his slower-ball variations while Walsh Jr marked his recalled with the key wicket of top-scorer Mitchell Marsh who looked to have put Australia on track with a maiden T20I fifty.