Reigning Formula One world champion Sebastian Vettel claimed pole position for the season-opening Australian Grand Prix, in a qualifying session unusually held on race day Sunday.

Vettel qualified in a time of 1 minute, 27.407 seconds around the Albert Park circuit, and was joined in an all-Red Bull front row by teammate Mark Webber, who was four tenths of a second back.

Lewis Hamilton qualified third in his first race for Mercedes, ahead of the Ferrari pair Felipe Massa and Fernando Alonso.

The second and third sessions of qualifying were postponed to Sunday after a series of rain delays and the onset of darkness prevented them being held Saturday.

Sunday's sessions were also held on a track damp from morning rain. In the second session, intermediate tires were used - except for McLaren's Sergio Perez who took an unsuccessful gamble on slicks - but the drying conditions meant the flying laps in final qualifying were all on slicks.

Vettel claimed the 37th pole position of his career, and his third in four years at Albert Park.

"It definitely wasn't easy in those conditions," Vettel said. "On the dries (tires) I got in the groove and the car felt in balance."

Under the F1 rules, the top ten drivers must start with the tires they finished qualifying on, meaning early pitstops will be required as the super-soft slicks are unlikely to last more than a handful of laps.

"It could be a couple of laps or a couple of laps more," Vettel said.

Mercedes' Nico Rosberg - who topped the time sheets in the first and second qualifying sessions - qualified in sixth, ahead of the Lotus pair Kimi Raikkonen and Romain Grosjean, followed by Paul di Resta of Force India and McLaren's Jenson Button.

- AP