The order as the race passed through half distance still suggested the race was McLaren's to lose, despite Vettel's pursuit of Hamilton, while Alonso had somehow hauled the recalcitrant Ferrari into fourth, ahead of Rosberg, Webber, Maldonado - who had emerged undamaged from his moment with Grosjean - Kimi Raikkonen, up from 17th on the grid, and Kobayashi, who was enjoying a spirited tussle with the returning Finn.
Alonso triggered the second round of pit-stops among the leaders, with McLaren opting to service its two cars at the same. That briefly allowed Vettel into the lead, but more tellingly for the Woking team, Vitaly Petrov's Caterham ground to a halt on the start-finish straight, prompting the first appearance of the safety car. Vettel pitted immediately and, while Button was able to regain his lead, Hamilton's luck again failed him, as the Red Bull slotted in between the two McLarens. RBR suddenly looked in good stead, as Webber closed in behind Hamilton, with Maldonado now ahead of Alonso, Perez and Raikkonen, as Rosberg dropped back to ninth, in front of Kobayashi.
Having been made to wait for the lapped backmarkers to work their way around to the tail of the field, Button paced the restart perfectly, pulling away from Vettel as the Red Bull struggled to get its tyres up to temperature. Hamilton had a look at retaking second, but was unable to make a move stick as second, third and fourth ran together.
The order, at the front at least, remained the same to the flag, with Button pulling out a couple of seconds over his pursuers. At the same time, Hamilton dropped away from Vettel by almost the same amount, leaving the Briton to defend from Webber, the Australian keen to finally land a home race podium. He was to be denied by just 0.4secs as the top four came home well clear of the rest, but still improved on his previous best Melbourne finish.
While Ferrari team-mate Massa retired after a clash with Senna, Alonso survived to take a fifth place that looked unlikely after qualifying. The Spaniard had to withstand prolonged pressure from a fired-up Maldonado, only escaping when the Venezuelan made an error on the penultimate lap, putting a wheel over the kerbs and being fired into a tankslapper that resulted in heavy contact with the wall.
That incident appeared to precipitate late chaos among the lower half of the top ten, with Perez and Rosberg clashing on the last lap. That not only left the Mercedes hobbling home with a puncture and the Sauber unable to resist the subsequent challenge from Raikkonen and Kobayashi, but saw Vergne briefly promoted to a points position - only to lose out to both team-mate Ricciardo and Force India's Paul di Resta, who went from 13th to tenth on the run to the line. Vergne eventually claimed eleventh on his STR debut, with Rosberg classified twelfth ahead of Maldonado, the two Marussias - which made it home despite very little pre-season running - and Senna.
Button's victory was not only the first time he had won at the same circuit three times, but also ensured that Vettel would not feature at the top of the standings for the first time since Abu Dhabi in 2010. The Briton will also hope that a record established over the past six seasons, in which the Australian GP winner has gone on to take the title five times, holds fast.....