Yuvraj Singh was India's hero yet again as the hosts ended Australia's 12-year-reign as World Cup champions with a five wicket quarter-final victory on Thursday.
The left-hander's unbeaten 57 - his fourth fifty of a tournament where he is averaging over a hundred - saw his team home after they'd been wobbling at 187 for five.
But India reached their target of 261 with 14 balls to spare.
Victory set up a dream semi-final against arch-rivals Pakistan in Mohali on March 30.
Australia captain Ricky Ponting scored his first international century in over a year in a total of 260 for six.
But it wasn't enough to maintain his team's bid for an unprecedented fourth straight World Cup title and fifth in all.
India, aiming for a first World Cup title since 1983, needed 54 to win off the final 10 overs.
Yuvraj eased fraying home nerves with a square-driven four off Brett Lee and, with erratic speedster Shaun Tait (one for 52 in seven overs) conceding 13 runs in the 41st over, the target became well under a run-a-ball.
Yuvraj struck a brilliant straight six off Tait before ending the match with a four off Lee.
He was well-supported in an unbroken sixth-wicket partnership of 74 by Suresh Raina (34 not out).
Ponting was previously involved in a controversial incident which could have seen Gambhir out for nought when he dived forward at square leg for a possible catch before suggesting he was uncertain as to whether the ball had carried.
The umpires referred the decision but replays showed the ball bouncing well in front of Ponting.
Opener Sachin Tendulkar looked in sublime touch.
But Australia denied him his 100th international hundred when he was caught behind off Tait for a fluent 53 during which he became the first batsman to score 18,000 one-day international runs.
Gambhir and Virat Kohli batted steadily in a stand of 49 before Kohli (24) slapped a full toss from part-time spinner David Hussey straight to Michael Clarke at short mid-wicket.
Now the question was could the remaining batsman avoid panic.
Unfortunately for India, left-hander Gambhir couldn't.
One ball after surviving a run-out, he set-off for a non-existent single and was well-beaten by Cameron White's throw to David Hussey having made 50 and been in a position to win the match for India.
Instead, at 168 for four, the pressure was back on India and that only increased when skipper MS Dhoni fell for seven after a cut off Lee was well caught by a diving Clarke at point.
Earlier, Ponting's 104 was his first hundred since he made 106 against the West Indies in a one-day international in Brisbane last year.
Ponting, who'd managed just 102 runs at 20.4 in five previous innings this tournament, had come into the match amidst reports he could be quitting international cricket completely after the World Cup.
Nevertheless the 36-year-old demonstrated his enduring class in a 118-ball innings featuring a six and seven fours.
He was out late on when he reverse-swept Ravichandran Ashwin straight to Zaheer Khan at short third man.
S. Watson b Ashwin 25
B. Haddin c Raina b Yuvraj 53
R. Ponting c Zaheer b Ashwin 104
M. Clarke c Zaheer b Yuvraj 8
M. Hussey b Zaheer 3
C. White c and b Zaheer 12
D. Hussey not out 38
M. Johnson not out 6
Extras (lb2, w9) 11
Total (6 wkts, 50 overs) 260
Did not bat: J Krejza, B Lee, S Tait
Fall of wickets: 1-40 (Watson), 2-110 (Haddin), 3-140 (Clarke), 4-150 (M Hussey), 5-190 (White), 6-245 (Ponting)
Bowling: Ashwin 10-0-52-2 (1w); Zaheer 10-0-53-2; Harbhajan 10-0-50-0 (4w); Patel 7-0-44-0; Yuvraj 10-0-44-2; Tendulkar 2-0-9-0; Kohli 1-0-6-0
V. Sehwag c M Hussey b Watson 15
S. Tendulkar c Haddin b Tait 53
G. Gambhir run out (White/D Hussey) 50
V. Kohli c Clarke b D Hussey 24
Yuvraj Singh not out 57
MS Dhoni c Clarke b Lee 7
S. Raina not out 34
Extras (lb3, w16, nb2) 21
Total (5 wkts, 47.4 overs) 261
Did not bat: Harbhajan Singh, R Ashwin, Zaheer Khan, M Patel
Fall of wickets: 1-44 (Sehwag), 2-94 (Tendulkar), 3-143 (Kohli), 4-168 (Gambhir), 5-187 (Dhoni)
Bowling: Lee 8.4-1-45-1 (3w); Tait 7-0-52-1 (2nb, 6w); Johnson 8-0-41-0 (2w); Watson 7-0-37-1 (1w); Krejza 9-0-45-0; Clarke 3-0-19-0; D Hussey 5-0-19-1
Result: India won by five wickets
Man-of-the-match: Yuvraj Singh (IND)
Umpires: Marais Erasmus (RSA) and Ian Gould (ENG)
TV umpire: Richard Kettleborough (ENG)
Match referee: Ranjan Madugalle (SRI)