India's gamble to bat first on a tricky wicket backfired heavily as they suffered a six-wicket defeat against Australia in the sixth cricket one-dayer to allow the visitors to clinch the seven-match series by taking an unassailable 4-2 lead. India captain Mahendra Singh Dhoni won the toss and surprisingly chose to bat first in heavy weather conditions and the side never really recovered from the early jolts to virtually serve the game on a platter to the worlds champions. It was a thoroughly professional display by the world champions,who first shot out India for 170 in 48 overs with their second-string attack and then chased down the target in 41.5 overs - losing just four wickets - to complete a facile win. On a track where ball turned sharply,Australia rode on Shane Watson's run-a-ball 49 and cameos from Ricky Ponting (25) and Cameron White (25) to inch closer to the target. Michael Hussey (35 not out) and Adam Voges (23 not out) then guided them home with 8.1 overs to spare. Earlier,a horror story unfolded after Dhoni's gamble to bat first on a wicket that offered generous movements boomeranged. India slumped to 27 for five in nine overs and a three digit total looked like a distant possibility at that point.