Australia trumped the West Indies by 39 runs in the third One-Day International at the Manuka Oval in Canberra on Wednesday to take an unassailable 3-0 lead in the five-match series.
After setting a target of 330 against the Caribbean side, the Australians bowled out the opposition for in 47.3 overs to register a win.
Earlier in the first innings, Watson hit a century on his return from injury and Phil Hughes cracked 86 as Australia scored a daunting 329 for seven.
Watson, opening the innings after five weeks out with a calf injury, smashed 122 off 111 balls in a welcome return to form before this month's four-Test tour to India.
