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Stand-in skipper Shane Watson chose to blame his bowlers, who were defending a target of just 155 on day three of the fourth Test against India.
India reached 4-158 off just 31.2 overs to win with more than two days to spare and sweep the series four-nil.
Sixteen wickets fell on day three on a turning pitch in Delhi which suited India's three-pronged spin attack.
India resumed on 8-266 and were bowled out for 272 including spinner Nathan Lyon's career-best 7-94.
Australia were skittled for 164 as man-of-the-match Ravindra Jadeja claimed 5-58 with his left-arm spinners.
Embarrassingly for the Aussies, tailender Peter Siddle (51 and 50) top-scored for the second time in the match.
It's the first time Australia have lost four matches in a Test series since going down 5-1 in the 1978/79 Ashes during the World Series Cricket days.
Chasing 155 to win, India lost 3-5 in a mini-collapse at 4-128 before MS Dhoni (12 not out) and Cheteshwar Pujara (82 not out) guided the home side to an historic series triumph, their biggest in a home series.
It was sweet revenge for skipper Dhoni after losing 4-0 in Australia in 2011/12.
"I thought we were definitely in the game," said Watson, who led the side in the fourth Test in the absence of injured skipper Michael Clarke.
"If we got to 150 and more if we bowled well on that wicket then we were going to give ourselves a very good chance.
"Unfortunately things didn't go exactly right with the ball.
"In the end we were very close."
Key batsmen Watson (averaging 16.50), Phil Hughes (18.37) and openers David Warner (24.37) and Ed Cowan (33.12) had modest series.
"We came here with high hopes of having a good series here and the four-nil here is what we deserved," Watson said.
"The Indians have totally outplayed us."
Clarke, who has returned to Sydney for scans on his back, was the only Aussie player to score a century in the series and topped his side's averages with 286 runs at 47.66.
Watson made a joke about his curse of having scored only two centuries in his 41-Test career.
"Hopefully I haven't rubbed off on too many of them because that would be a shame if they all get my disease," he said.
"For all of us as top-order batsmen, it has been very disappointing."
Watson said Clarke, who was Test cricket's leading runscorer in 2012, was in amazing form.
"We've all got to continue to strive for what Michael has been able to achieve as a batsman," Watson said.
"I'm the first one to put my hand up because I certainly haven't been good enough in this series."