By Nick Mulvenney
MELBOURNE (Reuters) - World champion Sebastian Vettel will start the Formula One season-opener from pole position on an all-Red Bull front row later on Sunday after posting the fastest time in the rain-delayed qualifying for the Australian Grand Prix.
The German, chasing a fourth successive world title this year, swept across the line in one minute 27.407 seconds to clinch his 37th pole as the flag dropped on the session, which was postponed from Saturday because of torrential rain.
"Definitely not easy in these conditions," Vettel said. "I had two good runs and on the drys I got into the groove.
"I am happy... but in a couple of hours the race is coming up, so it's head down again to get on with that."
Australian Mark Webber, still looking for his first home victory at the 12th attempt, also put in a blistering final lap on dry weather tires to finish second fastest in 1.27.827.
"It's going to be just another grand prix when the helmet's on," he said. "I've got to focus very hard on getting the most out of the strategy. A podium would still be good but the middle step would be sensational."
Lewis Hamilton (1.28.087) confirmed the pace of his car in his first qualifying session for new team Mercedes and was third fastest to take a place on the second row of the grid with Ferrari's Felipe Massa.
"What an incredible job the team has done to come from last year where they were struggling a lot," 2008 world champion Hamilton said. "I said yesterday it was a blessing that they had moved (qualifying) to today, and it really was.
"It's going to be massively challenging with the tires, I've already had graining," he added. "So that means I'm going to struggle to go as long as them in the first stint."
Brazilian Massa (1.28.493) needed a quick late lap just to get through to the final 10-car shootout but made the most of it to edge his twice world champion team mate Fernando Alonso by just three thousandths of a second.
"Looking at the conditions yesterday and today on the track, rainy and stopping, I think it was positive," Massa, who with Alonso missed out on the final session of qualifying in Australia last year, said in a television interview.
"It would have been very easy to not pass in Q2 (second qualifying session). I will try everything for the podium, to do a good race, a good start of the season."
Spaniard Alonso was fifth ahead of the Mercedes of Nico Rosberg, who topped the timesheets on frequent occasions during the sessions but could not quite get a good flying lap together once most teams had switched to dry weather tires.
Finn Kimi Raikkonen, who had also flirted with an early exit, will start from the fourth row alongside his Lotus team mate Romain Grosjean.
Paul Di Resta steered his Force India to the ninth quickest time to barge fellow Briton Jenson Button, the winner of three of the last four races at Albert Park, into the bottom spot in the final session, nearly three seconds off the pace.
The second and third sections of qualifying were postponed from Saturday because of torrential rain. The race begins at 5 PM local time (0600 GMT).
The rain was much lighter on Sunday morning but parts of the track were still wet, causing a few handling problems for the drivers as they started the day on intermediate tires.
McLaren's gamble on going for a soft tire suitable for dry conditions backfired when their new Mexican driver Sergio Perez was one of the six drivers to drop out after the first section.
"With hindsight, I think we should have switched back to the intermediate tire but we didn't," McLaren boss Martin Whitmarsh lamented. "So that was a shame, didn't come off for us. That took us out of Q3 with Sergio."
The team also gambled early on dry weather tires for Button in the final section of qualifying but the 2009 world champion was simply outpaced by his rivals as the session came to a close.
"When it's dry we don't have the pace," said Button, who must keep the same tires on the start of his car for the race.
"I'm surprised at how big the gap was because actually it felt like a pretty good lap. I didn't think the tires would be so grained, the rears are destroyed so it's going to an interesting start let alone the first few laps."
(Editing by John O'Brien)