Michael Schumacher may have snatched the fastest time of second free practice with almost the last lap of the day, but a torrential downpour between sessions meant that the German still came up short in his efforts to end day one on top.
Within an hour of the engines being silenced after the first real competitive action of the 2012 season, the skies over Melbourne darkened once again, with the clouds depositing monsoon-like quantities of rain on Albert Park and the surrounding area, flooding the city's temporary circuit and forcing armies of mop-wielding marshals into action at various points around the venue.
As was the case in session one, the precipitation had ceased before the cars took to the track again, but early running was limited by pools of standing water and the constant threat of the walls lining the circuit. Sauber duo Sergio Perez and Kamui Kobayashi were among the first to take the plunge, but it was Toro Rosso that again recorded the first timed lap, as rookie Jean-Eric Vergne recorded a tentative 1min 52.220secs.
The improving conditions soon made a mockery of that mark, however, with Vergne rattling off a sequence of substantially faster laps, even as team-mate Daniel Ricciardo was indulging in a major rotation as he caught one of the damper areas of the track. Vergne's reign at the top of the charts was eventually ended by Nico Hulkenberg, before Kobayashi got in on the act by taking the target below 1min 46secs.
The Japanese ace's Sauber team-mate was the next to visit the scenery, going off at turn 14 but managing to regain the tarmac without too much delay. Despite Perez's mishap, the circuit was now ready for intermediates to replace the full wet Pirellis. Fernando Alonso was the first to take advantage of the quicker rubber, taking the benchmark down to 1min 42.171secs, before Ferrari team-mate Felipe Massa began to atone for his first session trip into the gravel by replacing the Spaniard at the top of the pile.
Massa recorded two laps in the 1min 41s, before the evolving conditions allowed Pastor Maldonado, Jenson Button and Schumacher each took turns at setting the pace. Getting a wheel off line, however still provided problems, as Mark Webber found by running wide onto the grass and Schumacher replicated with wing-damaging consequences.
Perez and world champion Sebastian Vettel were the next to sample P1, with Romain Grosjean underlining Lotus' credentials by also sticking his nose in before Massa returned to top spot, the circuit now conducive to slicks. The decision then was whether to run on the harder or softer Pirellis, with the former proving to be the better bet for the best times as Paul di Resta and Schumacher showed by taking the target below 1min 31secs.
The Scot's team-mate then appeared to have the session sewn up by blitzing Schumacher's time and clocking 1min 29.292secs on the softer rubber - despite twice having had to back off to avoid catching Vettel before the end of the lap - but the seven-time champion hit back just as the chequered flag appeared - and Kobayashi endured a heart-stopping moment at the start-finish line. Schumacher's 1min 29.183secs effort was a tenth faster than Hulkenberg's, but not enough to topple Button's earlier 1min 27.560secs lap as the fastest of the day.
Perez produced his own late lap to claim third place in the second session, putting him ahead of Alonso, Kobayashi and di Resta, while Massa, Heikki Kovalainen, Nico Rosberg and Vettel filled out the top ten, and underlined the unpredictability of a session that had also seen Marussia's Timo Glock feature in the top three.... While the Banbury team had that brief cause to smile, likely rival HRT continued to struggle, with Narain Karthikeyan again stopping on track - albeit with 16 laps under his belt - and Pedro de la Rosa once more failing to set a time.
Saturday's forecast is for better weather, suggesting that a better idea of the true pecking order may be established ahead of the opening round of the world championship the following day.