BASSETERRE: Shane Watson kept his nerve, and the seventh-wicket pair of Denesh Ramdin and Darren Sammy failed to carry West Indies over the threshold, as Australia completed a thrilling one-run victory in the fourth One-day International on Friday. nnAustralia had set West Indies 283 for victory from 50 overs, and successfully defended the target score, when Watson - with the home team needing eight runs from the last over - conceded six runs from the final six balls. nnThe victory handed Australia a 4-0 lead in the five-match series, after they won the opening match by 84 runs in St. Vincent, the rain-affected second ODI last Friday by 63 runs under the Duckworth-Lewis Method, and the third ODI last Sunday by seven wickets. nnIt also set the Aussies up to make a swing at a rare ODI series sweep in the Caribbean. Only South Africa (5-0 in 2005) and Pakistan (3-0 in the same year) have achieved this in the Archipelago.